Blood Pressure Drugs May Prevent Headaches

NEW YORK (Reuters Health) - Findings from a large analysis of clinical trial data indicate that the use of blood pressure-lowering drugs can prevent a substantial proportion of headaches.

The fact that agents of different classes produce this effect suggests that the mechanism is the ability to lower blood pressure, lead author Dr. Malcolm Law, from London Queen Mary's School of Medicine and Dentistry, and colleagues note. Yet, findings from observational studies have not supported a link between high blood pressure and headaches.

The study, reported in the journal Circulation, involved data from 94 trials that looked at the four main blood pressure-lowering drug classes -- thiazides, beta-blockers, ACE inhibitors, and angiotensin II receptor antagonist. A total of 17,641 subjects received an active agent and 6,603 were given a placebo.

Treatment with a blood pressure-lowering drug reduced the top and the bottom reading of blood pressure by an average of 9.4 and 5.5 mm Hg, respectively, the authors report.

Overall, 12.4 percent of subjects given placebo reported headaches compared with 8.0 percent of those treated with an active agent, representing a risk reduction of 33 percent.

The authors estimate that about 1 in 30 subjects given a blood pressure-lowering drug benefitted by having a headache prevented. All four drug classes appeared to provide a significant reduction in headache prevalence.

"Blood pressure-lowering drugs are prescribed to reduce blood pressure and a person's risk of having a stroke or heart attack," Law said in a statement. "This result indicates that, as an added benefit, the drugs also prevent headaches."

Law conceded, however, that given the lack of association in observational studies, the present findings do not resolve the long-standing mystery of whether high blood pressure actually causes headaches.

SOURCE: Circulation, October 11, 2005.