Context: There is a paucity of effective, well-tolerated drugs available for migraine prophylaxis.

Objective: To determine whether treatment with the angiotensin II receptor blocker candesartan is effective as a migraine-prophylactic drug.

Design and setting: Randomized, double-blind, placebo-controlled crossover study performed in a Norwegian neurological outpatient clinic from January 2001 to February 2002.

Patients: Sixty patients aged 18 to 65 years with 2 to 6 migraine attacks per month were recruited mainly from newspaper advertisements.

Interventions: A placebo run-in period of 4 weeks was followed by two 12-week treatment periods separated by 4 weeks of placebo washout. Thirty patients were randomly assigned to receive one 16-mg candesartan cilexetil tablet daily in the first treatment period followed by 1 placebo tablet daily in the second period. The remaining 30 received placebo followed by candesartan.

Main outcome measures: The primary end point was number of days with headache; secondary end points included hours with headache, days with migraine, hours with migraine, headache severity index, level of disability, doses of triptans, doses of analgesics, acceptability of treatment, days of sick leave, and quality-of-life variables on the Short Form 36 questionnaire.

Results: In a period of 12 weeks, the mean number of days with headache was 18.5 with placebo vs 13.6 with candesartan (P =.001) in the intention-to-treat analysis (n = 57). Some secondary end points also favored candesartan, including hours with headache (139 vs 95; P<.001), days with migraine (12.6 vs 9.0; P<.001), hours with migraine (92.2 vs 59.4; P<.001), headache severity index (293 vs 191; P<.001), level of disability (20.6 vs 14.1; P<.001) and days of sick leave (3.9 vs 1.4; P =.01), although there were no significant differences in health-related quality of life. The number of candesartan responders (reduction of > or =50% compared with placebo) was 18 (31.6%) of 57 for days with headache and 23 (40.4%) of 57 for days with migraine. Adverse events were similar in the 2 periods.

Conclusion: In this study, the angiotensin II receptor blocker candesartan provided effective migraine prophylaxis, with a tolerability profile comparable with that of placebo.