Weight gain is a common side effect of headache prevention meds and a patient can gain enough that the weight itself becomes health problem. Today’s NY Times article, Is Your Medicine Cabinet Making You Fat?, advises patients who gain weight while taking a new drug to talk with their doctors about changing meds or strategies to avoid gaining more weight. This rather obvious advice is supported by current medical research that has docs worried about the cumulative effects of weight gain.
WebMD provides a list of specific side effects for specific headache preventives. ACHE lists side effects by type of drug and guides patients on what they should talk to their docs about before beginning a new preventive.