“Why did my doctor prescribe an antidepressant? I’m not depressed, I have outrageous headaches!” I’m convinced that every headache sufferer asks this question at some point. If doctors don’t explain the reasons or if patients don’t understand them, we feel dismissed or as if our doctors didn’t listen to us.
But there are good reasons behind the drug choice. Some of the same brain chemicals are thought to be shared between the two diseases, so antidepressants can adjust the imbalance of migraine-related chemicals. Also, many antidepressants have pain-soothing properties.
Tricyclic antidepressants, including Elavil (amitriptyline), Tofranil (imipramine) and Pamelor (nortriptyline), have a long track record in treating pain. SSRIs, like Prozac, Effexor and Zoloft, don’t have as much proof supporting their efficacy for pain, but there is some evidence that they help reduce pain as well as treat other symptoms related to migraine, like anxiety.
Mayo Clinic provides an overview of why tricyclics are used for pain, how they work and side effects. The best description of SSRIs for headache that I’ve found is Headache 2005 from the Robbins Headache Clinic. Getting to it requires wading through a PDF, but it’s worthwhile. The SSRI information begins on page 32.
11/18/05: Turns out the chemical imbalance theory of depression is off-kilter. Antidepressants may work on the same areas of the brain affected by headache, but a chemical imbalance isn’t the place.