Blood Pressure Drugs Prevent Headaches

Oct. 10, 2005 -- The key to better headache treatment may lurk in common blood pressure-lowering drugs.

A provocative new study shows four completely different classes of these drugs prevent headaches. That suggests an obvious conclusion to researcher Malcolm Law, FRCP, professor of epidemiology at the University of London.

"My best guess is that higher blood pressure does cause headache -- but that is a guess," Law tells WebMD. "We can't exactly shout from the rooftops that high blood pressure causes headache, although we think it probably does."

New Look at Old Debate

The idea that high blood pressure causes headache is nearly 100 years old. But later research usually failed to find more headaches in people with high blood pressure.

Law and colleagues suspected these studies simply missed their target. To rekindle the debate, they looked at 94 studies of four different kinds of blood pressure-lowering drugs: beta-blockers, thiazide diuretics, ACE inhibitors, and angiotensin II receptor antagonists.

Overall, the researchers found that people who got the blood pressure-lowering drugs reported 33% fewer headaches than those who took placebos.

However, Law doesn't suggest that blood pressure-lowering drugs would make good headache pills.

"It is likely that high blood pressure does cause headache, and taking a blood pressure-lowering drug does lower headache risk," he says. "But I do not think the first line of treatment for headache is taking one of these drugs. An aspirin is probably better."

The drugs, Law points out, reduce headaches by only a third.

"If you are getting a lot of headaches and need treatment, you would hope for a treatment that would prevent more than one in three of your headaches," he says."

Law and colleagues report their findings in the Oct. 11 issue of the journal Circulation.

Long History of Migraine Prevention

There may be another explanation for the study findings, suggests Donald Penzien, PhD, director of the head pain center at the University of Mississippi in Jackson.

Beta-blockers and calcium-channel blockers -- time-tested classes of blood pressure-lowering drugs -- have long been used to prevent migraine headaches.

"Beta-blockers for many years have been the gold standard of preventive treatment for migraine," Penzien tells WebMD. "For many years that was the drug of choice for prevention of migraine. Often the person who gets migraines has normal blood pressure, but the blood pressure-lowering drugs still work."

Doctors are only recently beginning to appreciate how common migraine headaches are. Many of the headaches reported in the studies analyzed by Law and colleagues may actually have been migraines, Penzien suggests.

There is indirect evidence this is so. Beta-blockers, Penzien says, prevent about 45% of migraines. Law's team found that beta-blockers prevented 47% of migraines.

Penzien says that migraines probably start in the brain, not in the blood vessels.

"We are pretty well convinced that migraine is more something going on in the brain, and the blood-vessel changes we see may be secondary to another brain phenomenon," he says. "Maybe the things about these drugs that affect blood pressure also affect the brain."