Diet, Patient Education, Treatment, Triggers

Testing if Your DAO Level is Low

Yes, there’s a test that measures diamine oxidase (DAO) levels in the blood. No, it’s probably not worth your time or money to get it done. (Wondering what DAO is? Start reading here and follow the links at the bottom of that post for more information.)

There are two issues. The first is there’s no well-established range of DAO levels. There’s speculation and you’ll find ranges listed, but they aren’t yet backed by solid science. Also, it’s not known whether the amount of DAO in your blood is indicative of how much is in your gut, which is where it really matters.

Genetic testing can show if you have mutations in the genes related to DAO production, but not how much you actually produce. While the test confirmed that I probably make insufficient amounts of DAO, dietary research, an elimination diet and testing DAO supplements were more informative.

The best way to find out if you’re low in DAO is to try taking the supplement. You can get small a bottle of the highest strength DAO for about $30. If you’re going for a high dose, use Histamine Block rather than Histame. (The Amazon link defaults to the more expensive 60 capsule bottle. Click on “30 Easy-To-Swallow Vegetarian Capsules” in the box below the “in stock” notice to choose the less expensive bottle).

It took about a month of playing with the amount of DAO I took and how long before meals to take it before I hit on the right set up for me. The label recommends taking two no more than 15 minutes before every meal. I’ve found each capsule covers about 400 calories, though I take more if I’m eating a high-histamine food, like fish. I currently take it about 8 minutes before eating (or even drinking coffee or herbal tea) and am sure to finish eating within 45 minutes. As you’ve read, the change was drastic once I hit on the right combination.

This was while eating a low-histamine diet, which I recommend trying. Even if you don’t, read the list of high-histamine foods and take extra DAO when you eat them. (Some of those foods are also high in tyramine, which has long thought to be a migraine trigger. DAO does not help process tyramine and there is no digestive enzyme that claims to.)

The capsules are expensive (about $1 each), so I initially felt a lot of pressure to take no more than I absolutely needed. For the sake of dietary variety, I’ve relaxed a bit and now err on the side of too much with foods I’m uncertain about. Other than pocketbook pain, I have no noticeable side effects. I thought heartburn was an issue for a while, but that has resolved (it was likely due to reintroducing fat after going so many months on a very low fat diet). I’ve been reassured that DAO is safe and that any that’s unused gets flushed right out. That’s why you have to take it before every time you eat — it doesn’t stick around.

I know many of you are hoping that DAO will help you as much as it has me. If you do decide to try it, play around with dosing and when you take it. If you get any relief from it, it might be another addition to your treatment plan. Every little bit adds up.

Still have questions? Please ask them in the comments or email me at kerrie[at]thedailyheadache[dot]com and I’ll try to answer them.

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79 thoughts on “Testing if Your DAO Level is Low”

    1. Hi Kimberly, the one I used isn’t available anymore, but they’re all similar. Make sure it contains diamine oxidase and you’ll be good to go. I hope it helps.

      Take care,

  1. Hi. the link at beginning of comment section on minimising amines in eggs meat etc no longer works- do you have an alternative to that?

    Also, what happens if you try to eat the powder in the DAO capsule? is it too acidic or otherwise inflammatory for someone who alrady has esophagus issues (perhaps from mast cell…)

    My issues may be more tyramine than histamine but figure DAO is worth a try- if I can tolerate it… (that’s a big “if”)


  2. I am having many food sensitivities/intolerances. I have had CFS/Fibro/MCS for years. What I found that not too many people talk about is how perimenopause and menopause affect food sensitivities. I am 48 yrs old and perimenopause can start as early as 35 and continue for ten years or so. The lowering/ rising of estrogen can cause sensitivity issues as we have these receptor sites in parts of our bodies outside the obvious places. I say this to say that women in the appropriate age ranges should look into this as a possibility. In any case thank-you for your article.

    1. Thank you for your comment Samantha. I have been gf for almost 2 decades but am not reacting to everything. I have thought that estrogen was playing a part with various issues going on right now. Appreciate the input. <3 Amanda

  3. This sounds exactly like what is going on with me. After spending a lot of time on an elimination diet, I’ve narrowed down my symptoms to Candida and Histamine. My ND and I are still sorting it all out but I will feel fine in between meals, then when I sit down to eat, about ten min in I feeling I’m having an adrenal response, nose gets stuffy, heart rate increases. It almost doesn’t matter what I eat either, of course high fodmap foods make it a lot worse. I think this might be the last piece of the very large puzzle. If any of this sounds familiar, please respond. I’ve spent years and years and so much money trying to figure this all out.


  4. Hi Kerrie,
    I’ve been someone with inflammation issues in various parts of my body for a long time. I’ve had IBS and GERD-like symptoms on and off for years (although mostly they were controlled with eliminating a few things like soft cheeses, too much sugars and drinking peppermint tea). Then in 2013 I developed Interstitial Cystitis out of nowhere. Many scientists now believe that it has something to do with deregulated histamine in the bladder. After a year of the worst pain I’d ever experienced, I got on a supplement called Cysta-Q,a herbal compound pill (whose main 2 ingredients are quercetin and bromelain) and I’m happy to say that, along with physiotherapy, it restored my life back to me-yay! After a few years of limiting highly acidic foods (that are also high histamine, come to think of it), I was able to add a few back in. I now completely avoid caffeine, tomatoes (although a few bits raw is okay now), restrict chocolate to a few bites once in a while, cayenne pepper and chili powder, strawberries, citrus (except small amounts of lemon and lime) and I was living pretty much a normal life.
    Fast-forward to this april when I got a stomach bug I couldn’t shake. Now I’ve got major GERD symptoms that don’t respond to traditional therapies, nausea, diarrhea, and hot flushes occasionally. All supplements and food to aid digestion actually make it worse (Kefir, probiotics, Betaine HCL and digestive bitters). I’m thinking of asking my naturopath to test histamine levels; what test would make the most sense to ask for-something to do with DAO or something else?
    Thanks 🙂

    1. Hi Laura, what an ordeal. I’m sorry to hear your symptoms returned. Your naturopath is better suited to help you determine what tests to try. It’s been a while since I’ve done research on this, but my understanding is that trying the DAO supplement and seeing it if works for you is just as informative as testing DAO levels. Best wishes in getting this sorted out.

      Take care,

  5. I need a DAO supplement like Histamine Block but can’t take anything with porcine which is an ingredient in that item. Do you know of a histamine block supplement made with pea or vegetarian ingredients? I know I can make them with pea seedlings but its a 10 day process and I need something ‘now’. Thank you for any help you can give.

  6. If you think you have a reaction/symptom to histamine, can you take some Diamine Oxidase
    to counteract the reaction/symptoms or do you have to take it before ingesting foods with histamine
    Or can you take it after the fact

  7. Hi Kerrie,
    Your article is very well written.
    I have body aches, fatigue, gastrointestinal issues, headaches, rhinitis, icthy scalp, dry or watery eyes, brain fog, anxiety. I have these symptoms every day/often for 7 years but hives I get only once a year.
    I wonder if I can have Mass cell Activation disease or histamine intolerance.
    What do you think?

  8. Can you please tell me what this comment means?
    “Click on “30 Easy-To-Swallow Vegetarian Capsules” in the box below the “in stock” notice to choose the less expensive bottle).”
    Is it on Amazon? Is it the same name brand?

  9. I am wondering if you can help me. I’m looking for a supplement or prescription that has DAO in it. I see you recommend Histamine Block, but everywhere I go online it says it’s not in stock … anywhere else you could point me?

    1. Hi Jenny, Histamine Block appears to have been discontinued. This appears to be the only DAO product currently for sale in the US: Note that if you search for DAO or diamine oxidase, multiple products come up. Be sure to read their ingredient lists carefully as few (if any) actually contain any DAO.

      Take care,

  10. Hello from the UK. There’s a good product which contains Daosin plus some vitamins and minerals. It is called Migrasin and is manufactured in Spain. It is available online and from some Spanish pharmacies. I have serious histamine issues and daily migraines, even on a low histamine diet. I find Migrasin puts away my migraine and means I rarely need medication now. I was taking a lots of migraine drugs in order to function. Migrasin, like Daosin isn’t cheap but it’s good to have something else up your sleeve. I also take Daosin before meals.
    I am currently trying out L-lysine for hives. Fingers crossed.

  11. Like others who have recently posted, I’m having trouble finding a DAO supplement that’s in stock. I do find several products that vitamins (like those Kerrie posted links to) but do not contain DAO. Does anyone have any information or experience with one versus the other?

  12. First, I want to say thank you for all that have contributed here. I have found this thread to be so very helpful. I began using the DAO supplement several months ago and although it was somewhat expensive, it was SUPER effective! It helped my IBS-C, psoriasis, headaches, and brain fog. I can no longer find it!! I have contacted every company that I can think of and I have gotten nowhere!! It seems so odd that this supplement would suddenly become unavailable. If anyone could share their source of DAO or perhaps provide some insight as to what is happening with the availability of DAO. Its so terrible to find something that helps so much and then find it unavailable. Thank you!

    1. Hi Lou, I’ve run into the same problem–it’s so frustrating and scary to think of being without it! DAO has been going in and out of stock for the last year no matter the company that makes. I think there must be a shortage in the supply chain. Here’s one that seems to still be in stock: Histame has been in very short supply for years, but one company on Amazon claims to have it in stock: If there’s a naturopathic college near you, they may carry DAO in their dispensary. I’ve also check Google regularly to see if any of the companies it lists have it in stock. I find it occasionally.

      Take care,

  13. To everyone dealing with Migraine read “Heal Your Headache:1-2-3 program” by David Buchholz. It changed my life. No more headaches/migraine! Just look at the reviews on Amazon.

  14. for those that think they have MCAS or mast cell disorder have you had your tryptase or zonulin level checked???

  15. i am so glad that i found this site…i have been having issues with food sensitivities my whole life but after last year it seems like everything has gone down hill. i cracked a tooth eating honey bunches of oats last february. when i went to the dentist he missed the fracture and just shaved it and put a cap on it…it still hurt, then he did a root canal…it got infected and i was given the first of 8 antibiotics in one year! after that didn’t work he said it needed to come out and i needed an implant, i said ok because i was only 32 and didn’t want to be missing a tooth. during the extraction he perforated my sinus with the drill, i choked on my sinus fluid and almost passed out. he put his hands up and looked aghast. then he placed the implant. i left feeling ok but for EIGHT months things got so bad i thought i wasn’t going to make it. i had nerve damage in my face and felt like someone was pouring cold water on my brain. i got so dizzy i could hardly stand. the dentist refused to remove the implant. i had to call 11-12 oral surgeons until i finally found one that would remove it. well, a cyst grew on top of it and while taking all those antibiotics i FRIED my gallbladder and had it removed two months after the implant was removed. NOTHING has been the same since. i have tested positive for 16 food allergies via igE (albeit low all are less than .27 i’ve seen 4 allergist and 3 have said the levels are too low to have reactions and refused to continue to see me. i’ve had two anaphalactic reactions where my throat got tight but i could breath the other time i was covered in hives on my left side of my body. OMG the hives i get hives for days or weeks at a time. the right side of my tongue CONSTANTLY burns or at least it feels like it tongue is constantly covered in white.) everyday i seem to react to something new. i get hives on my knees after taking hot showers. i’m allergic to a lot of medications now…i get so depressed i feel like i can hardly breath. last year i weighed 148-152 now i’m down to 121 and i can’t gain weight to save my life. i’m igE positive to wheat barley oats rice tomatoes celery cherries bananas garlic spinach sesame seeds peanuts sunflower seeds watermelon blue mussels …i can’t remember the rest. i cut out the wheat and lost 15 lbs in less than a month my stomach was no longer bloated FOR A LITTLE WHILE. i drank bone broth but it didn’t help. i’ve since gone back to eating some wheat and some of the things i tested positive for. i try to rotate as much as possible. i don’t want to cut things out anymore because then more things seem to bother me. i want to try DAO so bad but i’m scared i’ll have a reaction. i take mega food daily vitamin and ester c daily. i pray everyday i get through this…the brain fog, constant itching, itchy ears, flaky scalp, acne on my back, hives like clockwork at 1 am and fatigue are destroying my life. i have two little boys and used to do so much with them…i hope it helps me. I’m going to pick some up tonight at whole foods. i’ll post my progress. i’m going to ask my allergist to test my inflammation markers C1-INH my total IgE is 179. not crazy high but it should be below 114.

  16. Hi Kerrrie, I’m so glad I found this post and to hear of so many people’s plights. Mine has been no different. When I look back I can see I probably suffered with HI even as a baby as I was sick after drinking milk and my mum said I was very difficult to wake up – no doubt because the milk was just knocking me out and making me slugglish. I still have similar symptoms now with any food that doesn’t agree with me – I find it difficult to wake up on a morning and rarely do I feel refreshed and raring to go. As a young child, I was picky eater probably because I somehow knew certain foods just made me feel bad. Then at 2/3 years old I was given Penicillin for an infection and nearly died. Everytime I went abroad, I would end up with itchy rashes and water blisters. Things calmed down as I got into my teens but after I had my children I developed eczema on my face that I found difficult to control, then I developed IBS and ended up cutting out cheese and tomatoes. This greatly reduced my symptoms and eased my eczema but it wasn’t to last long. Then a homeopath advised that I rotate my food and never eat foods from the nightshade family together. This did help. Although I avoided dairy, tomatoes and bread/wheat, I still had a massive crash about 6 years ago. I was also pre-menopausal so my body was all over the place. I suffered with debilitating fatigue and brain fog and was unable to work. My body felt toxic. I tried taking chlorella to help detox my body but it gave me tunnel vision and I nearly passed out – I think too many toxins were being released in one go, that’s why I felt so bad. I’ve had diarrohea one minute then constipation the next. It’s taken me several years to recover using different herbal remedies and supplements together with a restriction on some foods, and I’m still battling with foods. I am unable to tolerate alcohol. My symptoms range from blocked stuffy nose,swollen eyelids, puffy body, tinnitus to even deafness in my right ear, brain fog and loss of concentration and flushing that I think is related to histamine not the menopause. My energy is alot better but I still have problems in the morning, it takes me a while to come round. By the end of the day, I have put on several pounds and my bra etc feels very tight. The foods I don’t eat are on the list for being high in histamine and I do believe that has been my problem for many years – histamine intolerance. The effects of certain foods can last several days – the other day I was out and I ate some bread because I was hungry. I still have symptoms and that was 3 days ago! I am also a very bad traveller on planes, boats and carts – I get travel sick. I do suffer with migraines on and off as well. I also have hives/pimples on both my arms but it is hardly noticeable, only when I am in a certain light can the pimples be seen. I have tried a variety of alternative practioners but none have got to the bottom of my issues. So I’ve taken matters into my own hands and have been taking a herbal detox mix and have started taking Mangosteen Powder and these have made a difference but not enough because if I do happen to eat something my body doesn’t like, I get some of the symptoms but not as intense. This shows me that what I’m doing is working and that I’m on the right track. I am hoping the dao will help even more so I can have a normal life instead of worrying about food all the time.Its taken over my life!. I would love to be able to wake up refreshed and to have good energy levels. I have a very healthy diet and I don’t want to go down the route of cutting out more and more foods because this too is damaging. I’m so glad I am able to share my story so far with others. It’s a lonely world when no-one is able to get to the bottom of these debilitating symptoms and doctors just want to give you a pile of pills for each one of them.

  17. Which Histamine Block are you suggesting that’s not too expensive? (your tip advice “The Amazon link defaults to the more expensive 60 capsule bottle. Click on “30 Easy-To-Swallow Vegetarian Capsules” in the box below the “in stock” notice to choose the less expensive bottle” doesn’t seem to work anymore

    many thanks

    1. C, unfortunately, it seems to be out of stock. I have contacted the manufacturer to see what the issue is, but haven’t heard back. Here’s an alternative: I haven’t tried it as it contains quercetin, which is a migraine trigger for me, but the primary ingredient is DAO.

      Take care,

  18. I cannot find a DAO supplement that doesn’t contain sugar (or a form of it). Plus, many have some other nasties. Can you recommend any that don’t contain sugar/sucrose/etc.? Thank you!

    1. Kymythy, try Histame. It is the cleanest DAO supplement. It isn’t as potent as the others, so you may have to take more to have the same effect.

      Take care,

  19. A lot of times when you eliminate foods it seems it leads to more elimination and you are left with 5 things to eat. When eliminating dairy we were left with a vitamin D deficiency, even though we supplemented with 1000 IU’s a day. Vitamin D deficiency alone can lead to cancer etc. That’s why it’s so important to get blood work done, check for nutritional deficiencies. Find a doctor who will listen to you and run the tests. Sometimes you cant tell these things, they go symptomless. I am so sorry for your loss.

  20. My dear, sweet mom spent decades searching for the perfect diet that would cure whatever she perceived to be wrong with her, which doctors could not detect. She decided she had leaky gut syndrome and food sensitivities. So she eliminated everything. And what she did eat, she controlled the portions. She didn’t feel better, so she restricted more. This pattern continued and as hard as I tried, I could not talk her out of it. She improved her diet briefly under my care after she lost the use of her legs and almost died from electrolyte imbalance (she weighed 70 lbs at that time) but sadly she reverted to her old ways again and I could not save her. Cause of death was listed as malnutrition secondary to anorexia. The physical suffering this caused my mom and the emotional suffering it caused me is immeasurable.

  21. Hello everyone! Here’s my story. Picky eater all through childhood. Lots of french fries, candy, soda etc. Started drinking, doing drugs and birth control pills at 14. At 18 I got psoriasis. Stopped drinking & drugging at 27. At 28 diagnosed with psoriatic arthritis. Then got pregnant-all my symptoms went away! Then came back 100 times worse after my daughter was born. Started my homeopathic healing at 35 when I was diagnosed with parvo virus after my daughter had Fifth’s disease. Body was totally inflamed! Then came changing my diet, supplements and trying to heal my gut. The struggle is real! As my diet has improved so did my psoraisis and inflammation. At 51 post-menopausal suffered an allergic reaction to bee sting and then wasp sting. At 52 hives non-itchy thankfully- now 53 and 2 dermatologists, 3 biospies, my primary doc doing skin testing, 6 months of hives I have stumbled upon this blog and the menopauseconnection blog too thank God! I stopped cheese, tomatoes and bread immediately, chocolate is still hard for me. I started taking B-6 and L-Glutamine and Quercetin too. Then I ordered the DAO and olive leaf extract from Amazon. For the last 5 days I took the DAO with 2 of my meals and the olive leaf once in between and the hives are non-existent. Last night I had bread, cheesecake, chocolate and a coke. Needless to say I paid for that dearly- up half the night on the toilet and some hives on my stomach. All of this experience tells me I AM histamine intolerant and once again God, myself and all of you are going to heal me. Thank you all for your experience, strength, hope & information. You are ALL EARTH ANGELS!

    1. Leslie – you may know this but it is very common for allergy symptoms to dissipate during pregnancy. And your body makes a HUGE amount of DAO during pregnancy, either your body or the placenta. Probably to protect fetus from transferring the wrong things. So definitely speaks to your DAO function.

  22. Thanks very much Kerrie for your posts and everybody else who commented on this one.
    I think I learned so much about DAO reading your posts and the comments than if I had done all the research I usually do when I want to understand about something.
    I was just looking for correct dosage of DAO for my 11 years old daughter who seems to have everything that everyone mentioned they have apart from migraines. Food allergies, eczema, hives, itchy, hay fever, etc, etc. Did anyone mention ‘crocodile skin’: cracked, flaking, non-stop shedding skin??
    My daughter’s body seems to react to just everything. I don’t know anymore what food she can eat. The list of no-no food is so big that I can’t even think what is allowed for her.
    I thought I was doing well following the Paleo+Gap+blood type diets, now I was told by her doctor about food high in histamine. She’s going to live on supplements then.
    Anyway, she’s on the second day of DAO and just today her skin seemed calmed down. My doctor told me to buy the DAO, but didn’t tell me how to use it. Bless her!! I guess she knows I research about everything and lots of time I bring information that she didn’t know. She is an orthodox doctor very interested in natural healing. She was the one who said to stop gluten and other stuff when all the other GPs were still saying, “she’ll grow out of it”.
    By the way, though my daughter itches big time during the night, in the morning when she gets up her rashes/hives/urticaria seems calmed, under control. By the time she comes back from toilet (she sits there for about ten minutes to wake up properly), her skin has already started getting on fire. Any light on this??
    Thanks very much everyone.

    1. I too have an 11 year old daughter, Jane, with similar issues. I have been dealing with this since 6 mos. old. with just an itchy rash. She has been misdiagnosed all these years . Allergists, dermatologists etc. have not been helpful. Her legs and arms scarred from years of scratching. Everyday I wake up wondering what I will feed her. She recently started seeing an Integrative Md. who did blood work and discovered Hashimoto’s, an autoimmune disorder involving the thyroid. If you Google thyroid and your daughters symptoms, you may see it come up. Hypothyroidism involves many issues and symptoms. Jane is also deficient in Vit. D. That alone can cause auto immune disease. Just wanted you to be aware of this, and maybe have some blood work done. We just began DAO again, to see if it helps before we progress to the thyroid hormone medication. I am trying it at the end of the evening, when her digestion is slowest and I think the histamine from the day that didn’t get taken care of by her enzymes cascades at night to cause the night and early morning itchiness. It’s so expensive to use all day, so I thought I’d try this first as she is always itchiest at those 2 times. The thyroid hormone alone may help, but I want to see if this can be relieved first to know the role of histamine and to seek the root cause of the auto immune disorder. I never would have thought Thyroid, she doesn’t have the classic symptoms,but when a variety of tests were run it was clear. Just wanted to share this with you, in hopes to find your root cause too and maybe save you both time and suffering.

  23. I wondered how long you’ve been taking the DAO supplements? Sorry if I missed it elsewhere. Also, on a different note, I found some histamine test strips by googling but I think maybe they are only for sale in the fish industry and maybe not to regular people – yet. That would be pretty cool to have something like that to test food.

  24. Hi,
    Thanks for all the info. I’m working with leaky gut and stumbled on Hist Dao because I was having rashes and welts, fatigue and headaches that always seemed worse after eating. I’ve been taking it for a couple of days and it’s been fantastic. My symptoms are down and I feel like myself again. However, I’m not pooping. It’s been 3 days and that is not normal for me at all. Typically I poop 1-3x’s a day. Any ideas or suggestions?

  25. Hi,
    Thanks for posts. They are very informative and helpful. It seems I am not the only sufferer. From the last three years I am having hives on my legs and arms, extremely itchy, with sneezing, red and itchy eyes. I am taking allegra everyday from 2012. Whenever I stopped it the problem worsened. I had an allergy test and based on that my doctor asked me to avoid chicken, egg, coconut, to avoid dust and pollens and asked me to get rid of cats. Inspite of avoiding all the above mentioned things I am having the same problem. Recently I have noticed that I get hives and my body temperature rises instantaneously as soon as I take tomatoes, green tea, oranges, lemon etc. Am I suffering from histamine intolerance? I have PCOD too, for which I had to take metformin for one year. Are they connected? How long I have to take medicines to get rid of hives? It seems that I am allergic to most of the foods so I am really confused about what should I eat?

    1. Debolina, it definitely sounds like you could be dealing with histamine intolerance. It’s worth looking into for sure. I can’t answer your questions on specific drugs or treating hives. It was very helpful for me to work with a dietician to figure out which foods would be best for me to avoid. There are some foods that are definitely implicated in histamine intolerance, but many food intolerances are individual. It can take a while to sort them out, but it’s worth it in the long run. Let me know if you’d the the dietician’s information. Best of luck finding relief.

      Take care,

  26. I’m looking into the cost of the DAO enzyme for a friend who’s too sick to use computers. Does anyone know what company actually produces the supplement? My friend has dire financial challenges and her life literally depends on taking this. It’s terrible that she’s going to have to stop taking it because of money. It will leave her unable to function at all and I’m worried she may lose her will to keep going.

    1. Leslie,

      It’s sold by several different companies. The one I’m using now is sold by Health Naturally. Xymogen also makes one, but so do other companies. You should be able to find the manufacturers through a Google search or on Amazon. Best of luck to your friend. She’s fortunate to have your support.

      Take care,

  27. Hello ,
    I just wanted to say thank you for posting such great content on this subject . I am a Nutritional Therapist and unfortunately I also suffer from Histamine Intolerance . It has been quite a journey for me personally over the last 3 years since I had my first major reaction . I know now I was having other symptoms for some time ,but never made the connection.
    On top of being debilitating, it can be a very isolating to deal with such issues. Most of my nutritionist colleagues and even doctors have been completely clueless about what was going on with me . I have continued to research this from many angles and hope to gain a greater understanding not only for myself but for my clients as well. There is certainly a need for knowledgable practitioners when it comes to this as well as many other related conditions that seem to be frequently missed in traditional settings. It’s sad to think that the best information seems to be found on sites like this where lay people out of necessity have had to figure things out on their own. Of course , Its a good thing that we can freely search the internet and find such wonderful resources.
    Thank you for all you are doing 🙂

  28. Let me try that again… looks like several words were missing, feel free to delete my first attempt…

    Hi, I don’t suffer headaches, I found your site while trying to google the subject of whether DAO could stop working after a period of time. Very useful post and follow up comments thank you.

    If you don’t mind me asking, how much DAO do you take per day? Is it the same amount every day? I currently take 10k HDU 5 times a day, 5 mins before eating.

    My allergist has tentatively diagnosed MCAD (Mast Cell Activation Disease) because of how well I have responded to DAO, and then a month later we added Cromolyn Sodium. DAO metabolizes histamine, and Cromolyn Sodium inhibits mast cell activity, so as I understand it I guess my mast cells are way too busy, and Cromolyn stops mast cells releasing histamine, while DAO metabolizes the rest of it. Theoretically.

    For 5 weeks, I was feeling better than I have in absolutely years… until 5 days ago when suddenly all my symptoms came back overnight, really weird and very unpleasant. So that’s why I was googling to research whether anyone has report DAO “pooping out” as I’ve seen it termed.

    1. Katie, I’m sorry you’re symptoms have come back. This is something I’ve wondered about myself. I take about twice as much as you do each day. DAO doesn’t change anything in the body, so there’s no reason it should just stop working. It also doesn’t stick around after digestion, it just does its job and moves on. I don’t have a mast cell disorder, just underproduction of DAO, so we could have different reactions to the DAO. I wish you all the best in getting this sorted out.

      Take care,

      1. Thanks for responding Kerrie. Your comments about DAO are very useful. I may also try taking more, I think I read somewhere that it’s ok to take up to 14 or 15 capsules a day.

        My symptoms returning turned out to be my mast cells being “triggered” after exposure to a powerful RX anti-fungal cream. I’m extremely sensitive to chemicals, meds, perfumes, and even the slightest exposure can trigger all my symptoms to return. My diagnosis is very recent, so I’m still learning how MCAD goes for me. It seems DAO and Cromolyn keep mast cell release and histamine activity in check nicely for me, unless I get triggered, in which case they both stop working for about 5 or 6 days.

        1. Kate,

          Thanks for checking in. I’m so glad you figured out what the recent issue was.

          For me, one capsule is good for about 400 calories, though I take more when I eat something high(er) in histamine. I wind up taking so many in a day because I eat small amounts throughout the day.

          Take care,

  29. I’ve done DNA testing via 23 and me so wondering which snp s indicate if I have a genetic disposition. Google wasn’t helping so hopefully you have tips or links to figure it out.


  30. I’m using Daosin since 4 month and I’m so happy to have it! Yes the supplements are sourced from pigs, but we have so many supplements or medicin which gets sourced by animals! Anyway, we should be glad to have sth to make our life more better! 🙂
    best wishes,

  31. Thank you for sharing your experiences and information gathered.
    I was considering trying the DAO supplement after lifelong histamine sensitivity but I cannot find anywhere that tells me how it is produced. One user has told me she reacted to it and was guessing that it was because it is sourced from pigs. I have the tick born alpha-gal allergy and cannot use any animal products. Do you know how DAO is produced for supplements?
    Many Thanks,

  32. Hi Kerrie, Thank you for sharing your information. It is such a big puzzle and any piece I find is valuable. I did want to suggest that you find out more about the role of gut dysbiosis and food intolerance, with particular reference to amine intolerance, especially histamine. I saw you mention the Friendly Foods/Failsafe diet which I was on for a number of years. This helped, but my range of intolerance steadily got worse. This is because my intolerance is caused by damage to my gut wall, caused by the wrong sort of microbes getting out of balance in my digestive system. This damages the cells that create enzymes to break my food into bits I can deal with. The Friendly foods diet is high in starch, refined sugars and flours. Higher than a normal diet. This feeds that bacterial overgrowth.

    I studied ecology at Uni and there are many studies that show that nutrient overload in a system leads to a large decrease in species diversity and an increase in a small number of opportunistic species. Combine this with events where we use antibiotics, this is like spraying herbicide on your garden, leaving it bare then continually applying fertiliser. You will get an excellent crop of weeds. So the Failsafe diet might remove the thing you can’t digest well, but it can further damage your system. I feel it is better to treat the cause not the symptoms.

    The GAPS diet protocol and the paleo auto-immune diets are two diets that are aimed at fixing this issue, the gaps diet also includes a probiotic protocol to replace gut flora. However, for someone with amine sensitivity, you need to adjust to reduce the amines at the start or use something like Histame. Otherwise the symptoms are very strong whilst your gut is healing. The people who advocate this diet are not that great with their knowledge of histamine intolerance, as they often think anything uncomfortable is die off and they do not understand how debilitating histamine can be. However, I think that this is the best bet to provide a long term solution for best health. I have seen many testimonials where people have reversed amine sensitivity, and I have even been able to eat cheese without symptoms, which always did me in.

    However, I no longer can as I have another issue. I think I have a bug in my gut that digests histadine to histamine (many bacteria do) and now I have the same response to protein as I used to have to high histamine food. I haven’t worked out how to fix this one … yet. 🙂 Good luck with all you do, and again, thank you for the time you have put into this page.


    1. Sarah, thanks for the kind words and all the information. I’m still getting the dietary stuff sorted, but am doing better than I have been. A reader mentioned that she did really well with DAO and, at her pharmaceutical chemist husband’s urging, started a probiotic and is doing great with it. There are so many potential avenues to explore!

      Take care,

  33. Hi Kerry, I found you via and wanted to thank you for writing about histamine, and such a well-researched article! Very helpful and informative. I agree there is so much conflicting information out there. There is ONE book that only talks about histamine: The Complete Migraine Health, Diet Guide, and Cookbook. It does have a lot more details about histamine. However, the recipes (which are culled from other books by the publisher) do include many known migraine triggers, so I haven’t been recommending it for that reason.

    I am working on an 8-week migraine diet program and found your research very, very useful. Thanks!

  34. As promised, I’m getting back to you about my results after trying doa for just over a month. Unfortunately, it has not resolved my biggest complaint which is the ugly swollen tummy. I guess I was hoping for miracle results in that department. Although it didn’t “cure” me overnight, I have noticed some definite inmprovements in the way I feel. First I tried eating anything I wanted with the doa. It stopped the feeling like My stomach would explode after every meal, although I still felt bloated and a bit foggy. I must let you know though that my brain fog is much, much milder with the dao before each food intake. The following week I went back to my regular regime, of probiotics, and eating a limited diet according to my extreme food intolerances and allergies. My tummy is not flat yet by any means, which is sad for me, but the swelling is down by at least 40-50%. This makes me happy because I can wear my clothes, and go for a dinner or BBQ with friends without feeling scared that my clothes will no longer fit me due to swelling, if I eat with them. My tummy still swells a bit, but it doesn’t put up a dress size like it used to. This in itself is a huge enhancement in my life. It is wonderful and it’s very exciting. I’ve also noticed that my constipation issues are different. I can’t say that they’re better, because I go from regular to the runs every other day or so, but I can tell you that it feels better than not being able to go at all. I am also very happy about that.
    I have also noticed that I no longer wake up with a dibilitating stomach ache every morning. I now have a very mild pain in my tummy, and once I take my florastor probiotics, it gets milder and then is gone after about 20 mins. This is compared to one to two hours of suffering and not being able to get anything down every morning for the last 4 years or so. So dao wasn’t a miracle pill for me, but it has definitely made some improvement in my life.
    After working to heal my gut with little to no results for the past 9 months, my naturopath supported my descision to try dao, this has also given her a new direction to look at. She is getting some tests done this week to see if any of my other organs are compromised.
    I read somewhere that it is important to change up digestive enzymes every few day or few weeks to prevent oneself from developing allergies to them. This worries me a bit, because I’ve tried other digestive enzymes in the past and never seen results like I have with this Dao stuff. I hope I do not develope an intolerance or allergy to it because that would suck.
    Thank you for posting that enzyme page, I will take a look and investigate some more.
    I hope this post will give someone considering this supplement some insight into how it works. I also want to thank you again for your blog.

    1. Thanks for the detailed update, Jennifer. I’m so glad it has made an improvement, but sorry you’re still struggling. I’m doing some fine-tuning myself… I sometimes wonder if I will be for the rest of my life!

      Your description of your response to DAO made me wonder if you have something going on down the chain from DAO. I’ve just learned that after DAO does it’s work, it results in by-products that your body needs to process. I can’t find the details right now, but your naturopath might be able to help.

      I haven’t seen anything about developing intolerances or allergies to digestive enzymes. And I’m not going to look too hard because it’s not something I want to think about right now — it would totally suck if it stopped working! I did see this reassuring summary of whether digestive enzymes ever stop working:

      Best of luck getting things sorted out. I’m glad you’ve made some progress and I’m rooting for more. Please let keep us posted.

      Take care,

  35. Thank you for all your posts. I had a swollen tummy my entire childhood, I used to see the starving African children and say why do I look more like them than the people around me. I went to a naturopath at 19 and began my long journey into “getting rid of my allergies.” I did so many eliminations diets and probiotics. If you are what you eat, I should be a probiotic. Instead of my symptoms improving, I began having migraine headaches along with my hayfever. Then my list of food intolerances went sky high. I am 41 now, and I’m intolerant to 95% of the foods on my naturopath’s food list. My stomach still bloats about 2-5 times per week, and although my migraines are much less intense since I had my wisdom teeth removed, I still deal with brain fog and extreme headaches, and body aches, particularly my kidneys; and it’s usually tied to food. My migraines and food intolerances get so bad during allergy season that I sometimes have to go for a few days with only water. I can’t eat or drink without triggering an asthma attack and or migraine attack. All my doctors tell me that food allergies and hayfever are not related in the body, but like one of your previous posters said, I believe it is all tied to the gut, and I can’t seem to heal my gut no matter how much I work at it. I’ve decided to try the doa and see if it helps. I’ll post you back in a month or so to let you know my results. I really want to thank you for all the work you’ve put into this blog. You’ve laid it out so well, and I understand the fear and frustration that you and others have experienced with medical doctors because I have had the same problems with trying to get my symptoms diagnosed. The food affects my entire body negatively, not just one part of it. And what may be a trigger me today may be fine to eat next week or next month, or it may trigger a completely different problem then. I just never know. But an enzyme deficiency makes sense. Again, thank you.

    1. Thanks for the kind words and you’re welcome. I’m glad you found it helpful. It sounds like you’ve been through a lot.

      Many of the diets intended to heal the gut are VERY high in histamine, so that could be feeding (no pun intended) the issue. Please do let us know how you do with the DAO. If it’s not DAO, it could be another enzyme deficiency. Here’s a good place to read more on that:

      Take care,

  36. Thanks for your reply in helping me better understand this enzyme. I received the Histame and found that the lower dose is MUCH better. So far so good. I do think I will take it even with meals that I would consider safe. I’d like to see if it would continue to degrade histamine in my blood even if it didn’t necessarily come from food.
    I sent some questions to a friend that happens to be a holistic consultant. She forwarded my requests on to one of her colleagues. From her reply, I learned that enzymes were a class of proteins. And that the belief was that histamine intolerance was rooted in poor protein digestion. Also, some concerns were that if one enzyme production was impaired, what others may be also.
    I do believe leaky gut is a big reason the food allergies keep getting worse. If DAO is made in the small intestine, and my small intestine is not in good shape, then I can see why the DAO production is affected. More inflammation, more partially digested proteins get into the blood, more histamine is released, and the production of DAO is impaired because of the inflammation so less of the histamine is degraded thereby remaining in the blood to wreak havoc with the rest of my body.
    I believe that h-pylori is the reason behind the upline action that caused the leaky gut. The HP lowers stomach acid, the lower HCL doesn’t digest the food properly before it leaves the stomach. The lower HCL also allows things to survive the stomach environment that should not, such as parasites, bacteria, and viruses. If these critters set of house keeping in the intestines, you will not be happy.
    I have taken digestive enzymes, HCL, probiotics, and have treated the H-pylori. It helped but wasn’t enough. I think I’ll continue, while supplementing with DAO, and hopefully see some serious progress. I might actually heal the gut and send this problem on it’s way.
    BTW, I heard that certain probiotics should be avoided when DAO is impaired. Which ones would these be?
    Thanks again. Teresa

  37. Thanks, Kerrie.

    I think I’ve had enough improvement with the DAO that I can’t just call it coincidence anymore. I haven’t taken it with every meal (or snack), just the times when I have something I’m not sure about. So I’m definitely still having headaches, but they are not nearly as severe as they usually are. In other words, I can still function, though I don’t enjoy the day. However, this is information, too. I read somewhere (don’t remember where) that vitamin B6 and vit C help support endogenous DAO production, so just started taking those today.

    I’m seeing some differences between various lists of high histamine/histamine releasers foods, as I’m sure you have, too. Makes it even more difficult. If you do put together a “master list” of foods OK for histamine-sensitive folks, I’d love to see it.

    Thanks again; I’m gradually starting to build some hope of a predictable-relatively pain free-life again.


  38. Thanks for your update, Kerrie. I’m trying the DAO supplement, and I think it’s helping (too early to say for sure, if the improvement if just coincidental). Animal protein seems to increase migraine for me, so I’m relying on legumes, too; a limited variety.

    As you expand your list of foods you tolerate, would you mind updating your list? Although there is a lot of individual variation, I still think that general tendancies will be fairly consistent, though may differ in matters of degree. I agree with Teresa, above, that experiences of other migraine sufferers has helped me more than the advice I’ve been given by various neurologists of the years.

    Also, do you take the DAO supplement before every meal, or only meals that you’re not sure about?
    Thanks a lot for all your postings and your very valuable insights into your experiences!!!


    1. Ann,

      Thanks for the kind words. I’m glad DAO seems to be helping you! I take it EVERYTHING I eat, even snacks or just coffee. Some people only need it before “suspect” foods, but eating anything triggers a migraine for me.

      I will update my food list, though it is still very limited compared to most diets. I plan to make a list of all the foods that are considered OK for most people with histamine issues, but am not sure when it will be ready.


  39. I came across your website today and wanted to say thanks for sharing your information. I’ve found that people’s experiences are as much if not more informative than all the scientific data in the world.
    I to have had reactions to various foods that once never bothered me. And I find that if I eat certain things once, it’s okay, but more frequently and BAM. It started slowly about 15 years ago, after I had a hysterectomy. It took a long time for me to figure out that the problems I experienced had to do more with what I ate and how my body processed the food, than some chronic “disease”. I read an article that spoke about how all the specialists only see what “they” had been trained to see. A cardiologists only sees issues with the heart, a gastroenterologist only sees IBS , and a neurologist only sees the headache and other related disorders. I don’t understand why such highly trained professionals have such a hard time connecting the dots. It wasn’t until I became frustrated with allopathic medicine and their puzzled looks when I’d suggest that there was something at the root of the things I considered symptoms and they considered diseases, that I finally sought a more holistic approach. Over the years I’ve tried many things, most of which have helped somewhat, for a while. The most progress was made through diet restriction and treating h-pylori. But, as with everything else, they only went so far, then back to the same old same old. I’m new to the DAO enzyme treatment and am searching for as much info as possible. I stumbled on it while searching a hunch about trying to control histamine and maybe that would be a way to stop the inflammation in my gut, then maybe the leaky gut could heal. Once this happens, I don’t think the foods will cause so much trouble.
    Here’s my initial thinking. The foods that are considered high histamine may also be related to Dr. D’adamo’s research on the lectins in foods and how certain foods react to your blood type. That would be the “Eat Right for your Blood Type” diet. When I had allergy testing done years ago, I found that most of the foods shown by the allergist as reactionary, were also on his list of foods to avoid for my blood type. Now after reading about histamines and the degradation of them, I do believe that somehow they are connected. That has always gotten me crazy looks from the drs when I told them my blood felt thick. And that is exactly what is happening from the lectins and the histamines in the plasma. Dry skin brushing has helped with the lymphatics to get things flowing better.
    I have many other thoughts about connections to things I’ve learned about over the years, so I think this has more than a single origin, at least for me. It is multifactorial, but not beyond correcting. Chinese medicine teaches that systems can be brought back into balance, and I believe that. I want to try and chart my history and see what that leads to.
    Are there any lists that may show spices or herbs that may trigger the need for more DAO? Also, what are the differences in the supplements for the DAO enzymes that are for sale? I saw one listed as 4000 HDU’s, which looked like it was 0.3mg. That would be about 300 mcg, correct? I ordered one from Swanson (DAOsin) which says it is 4.2 mg. That’s 4200 mcg. I wonder about the quality control of the manufacturers, of is the DAO derived all from the same place?
    This journey some of us are put on can be very frustrating, but we have a lot to learn from it. We should freely give of our knowledge and allow others the opportunity to learn and hopefully benefit from our experiences. Your posts are very helpful. I’ll continue to read through them. I may have other questions if you won’t mind me asking them from time to time. Thanks, Teresa

    1. Teresa,

      DAO supplements come down to Histame and all the rest (DAOSin, Histamine Block, HistDAO), etc. Histame has fewer inactive ingredients than the others, but is not as strong. Histame is about $0.80 per capsule and has 4,000 HDU, all the rest are about $1 per capsule and have 10,000 HDU.

      All DAO in supplements comes from pig kidneys, though I don’t know if they all use the same source. I believe that almost all the supplements (barring Histame and possibly DAOSin) are manufactured by the same company and sold under different names — the ingredient lists are identical and the capsules look the same.

      The food list ( includes herbs and spices to avoid. It’s mostly spicy things (with peppers) and the “sweet” spices (cinnamon, cloves, nutmeg).

      Best of luck sorting this out! I’m happy to answer questions.


  40. Thanks for all the info in your blog, we are going to try DAO and hope it will help with our issues.

    Have you tried diet changes other than eating low-histamine foods? There is evidence that migraines are an autoimmune issue, so diets reducing general inflammation will calm down the immune system and reduce headache frequency/intensity. Best resource along these lines is Sarah Ballantyne’s book, The Paleo Approach: Reverse Autoimmune Disease and Heal Your Body.

    In another gut/brain connection, people using digestive enzymes will often see improvement in their migraines. Karen DeFelice has some helpful books for this.

    1. Tim, please let us know how it goes! I’m trying to eat anti-inflammatory foods as well. Migraine can be triggered by autoimmune issues, but the underlying issue is a neurological disorder that also involves inflammation. This distinction is important to some, but not others!

      Thanks for the information.


  41. yes, kerrie, you always help! in my 45 years of migraine and sinus infections, hives and skin itching where there is nothing visible that should itch, i have also done a lot of research. 18 years ago i came upon the lyme disease connection, in the chronic form. no tests are accurate for that disease, and i was treated too many years after the (presumably) infected tick.

    i’ve given up multitudes of foods for many years, including fermented items, benzoates and all food chemicals. the lists of no-no’s for histamine and tyramine are so restrictive, and i will continue to keep these foods to a minimum. it is not possible for me to kill my own chickens or catch my own fish, though………

    it would be most helpful if you were to post YOUR present diet. i realize this is a lot to ask of you, since you already do so much in other related areas to help suffering people. what do you think? gratefully, dianne

    1. Dianne,

      I doubt my current diet will be too helpful for you! It is still very restricted as I’m reintroducing foods slowly. Compared to how little I ate for the last year, it is quite varied for me, but will look impossible to someone starting from a normal diet.

      Foods I can eat without restriction: cucumber, zucchini, cauliflower, kale, garbanzo beans, apples

      Foods that are OK in moderation: radishes, green bell pepper, peanut butter, artichokes, yellow lentils, black-eyed peas, mung beans, salmon, celery, carrots, broccoli, basil, peppermint, coffee, corn (Most are OK a few times a week, but corn is no more than once a week. That’s a red flag to me that I should probably avoid corn, so almost never eat it.)

      Foods I was OK with, but am now reacting to: all things coconut, butternut squash (It appears that I ate so much of these — coconut at every meal and an entire butternut squash a day that I developed a reaction to them. They are both very good to try… just don’t eat too much of them!)

      Some tips on meat/protein — Fish is easiest to avoid at first, but talk with the butcher counter at the grocery store to see if they can tell you when the chicken was butchered. You can also check with local meat producers (here’s a directory:, who can almost certainly tell you when the meat was processed. They may be more expensive than conventional grocery stores, but call or check their websites before assuming that. That’s what I did at first, now I’m getting almost all my protein from legumes. If you go this route, avoid red legumes (kidney beans, red lentils) at first. There’s nothing definitive, but some people with histamine issues seem to react to red foods. It is enough of a potential issue that’s it’s a good idea to add them to an already stable diet later.

      I know how frustrating it is to start this diet — it gets easier, I promise!


    1. A naturopath is the most likely person to do DAO testing, but if the supplement made you feel worse, it seems highly unlikely that your DAO is low. This is a very new area, so you may find even a naturopath can’t help much.

      The same goes with mast cell disorders — they are rare and not many health care providers specialize in them (and many don’t even seem to know about them). I saw an allergist/immunologist. The good news is that if headache or migraine is your primary symptom and you don’t have skin flushing, itching, hives or anaphylaxic shock, it is VERY unlikely that you have a mast cell disorder.

      If you only took the DAO in conjunction with the antihistamine, I recommend trying the supplement alone. Some people have a sort of rebound effect with antihistamines — the body knows it’s producing enough histamine and gets confused that it isn’t being used, so it starts producing even more. For some people, this happens immediately, for others it happens only with frequent use of antihistamines.

      In one of the bizarre variations of headache disorders, some people actually feel better when they ADD histamine. What’s working for me may actually make them feel even worse.


  42. I am so, so happy for you that you figured this out and are doing so well. I also feel quite immature for being a bit jealous. Just wanted to let you know that I think you are a terrific writer and I thought your recent post on hope was very good. Also wanted to thank you for trying to help me, through our email correspondence, recently. The DOA and Histimine Block supplements caused my head to hurt worse as most medicines and supplements do. I will now look into the mass cell diseases that you mentioned awhile back. Do you know which kind of doctor I should be seeing about this? My doctor said I should see an allergist. Last time I saw the allergist when I mentioned some things to him that were a little alternative/ homeopathic he was very uninterested.

  43. kerrie, you are doing a marvelous service for sick people with all your research. i’ve been trying (with my small knowledge at present) to be anti-histamine, and it has made an enormous difference in my energy level. since i still don’t know what i’m doing, and am finding it hard to find enough to eat for my out-of-control appetite (though i’m thin, i’ve always had a giant appetite). please advise me if you think that janice joneja’s book, which is 11 years old, is THE BEST reference. i am on the poor side of things, but can’t find it in my public library systems. i’ve done reading from UK doctors, and nobody seems to agree, which i understand. i just need some guidelines that i can actually follow. thank you so much!
    and p.s. i have not yet found the supplement to be useful. i can’t afford to take it every time i eat, so i’m trying to be much more savvy about eating the proper foods.

    1. Dianne,

      Dr. Joneja’s book is great, but the information on histamine is minimal and the food list is about the same as on the one I shared ( Here are a couple articles you might find helpful:

      In my consults with Dr. Joneja, she recommended I avoid histamine, tyramine and benzoates (more on benzoates:, all of which are covered in the food list above. I know the information feels sparse and confusing, but it really is as straightforward as follwoing the list and trying to minimize amine formation in food ( Please don’t confuse that with me saying it is easy! It isn’t, but it is fairly straightforward.

      Does that help?


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