This is a common question people ask when we suggest that they start taking a daily preventive medication.  A groundbreaking study just published by Hans-Christoph Diener and his colleagues answers this question.  Over 800 patients were placed on topiramate (Topamax), a popular epilepsy drug used to treat headaches.  After 26 weeks half of the patients were switched to placebo and the other half contined on Topamax for another 26 weeks without doctors or patients knowing who was taking what.  It turns out that stopping Topamax did worsen headaches, but not that much – in a 28-day period those on Topamax had one fewer day with migraine than those on placebo.  This suggests that what most headache specialists have suspected from their experience all along is correct.  That is many patients can stop taking their daily medication after about six months without significant worsening.  However, there are some patients who may need to stay on a medication for longerer periods of time.