Does menstruating cause headaches?
By the faculty of Harvard Medical School for The Harvard Medical School Adviser

Q: I seem to get more migraines around the time of my period. Why does that happen, and is there any thing I can do that can help?

A: There's a big gender gap when it comes to migraine headaches. Among adults, women are two to three times more likely to get migraines than men. The female hormone estrogen seems be one reason. Research shows that for some women, migraines are caused by the normal dips in estrogen levels that occur with the menstrual cycle. These menstrual headaches, as they are sometimes called, may be estrogen-withdrawal headaches.

In fact, almost half of women with migraines say they notice that the headaches occur more often around their periods. That's the time during the monthly menstrual cycle when estrogen levels are falling (see illustration). Migraine headaches usually cause a throbbing pain on one side of the head, most often near the eye or temple. Nausea and vomiting may also occur. Visual disturbances are common, sometimes occurring without head pain.

Some researchers believe that estrogen influences pain pathways by affecting the amount of brain chemicals that play a role in pain sensitivity. Other scientists suggest that estrogen may have a direct effect on blood vessels, perhaps by stimulating the release of a chemical that causes blood vessels to swell. When estrogen declines, blood vessels sporadically contract and expand. This may then lead to the throbbing sensation felt by migraine sufferers. Yet a third theory suggests that estrogen withdrawal triggers migraines by making the nerves in the face and scalp extra sensitive.

Women who take birth control pills experience rising and falling estrogen levels because the last seven pills in a 28-day pack are dummy pills that contain no hormones. As a result, women who take them may also be prone to migraines during the final days of their cycle. But several new types of birth control pills reduce the number of "off days" (without hormones). A product called Seasonale is designed to be taken for three months with only one week off. Earlier this year, the Food and Drug Administration approved Lybrel, a pill designed to have no off days. It completely eliminates menstruation.

Whether these new products will mean fewer migraines is still unclear, though. Several studies have found that women on continuous estrogen have fewer headaches and less severe ones compared with those using the traditional 21/7 formulations. But researchers have cautioned that these regimens are not a cure-all. As they point out, women often quit taking birth control pills because they believe the pills give them headaches.

Migraine sufferers should try to prevent attacks by avoiding things that trigger them. Common triggers include stress, changes in sleep patterns or caffeine intake, and dietary factors including red wine and aged cheeses. Women whose migraines seem to be related to estrogen withdrawal should be especially careful about taking these steps near their menstrual periods. Doing so might pull them back from a tipping point that triggers a migraine.

Some doctors ask women to keep headache diaries for several months. This can help them see how often their migraines happen close to or during their menstrual period. Although many women have migraines more often during their period, less than 10 percent have them only when they're menstruating. When migraines occur only with menstrual periods, several small studies suggest that taking nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen (Aleve), just before, during and after their periods, may head off attacks.

When migraines occur more often during the menstrual period, but also at other times, a variety of treatments have been found to reduce the frequency of migraine attacks. These include ACE inhibitors, angiotensin receptor blockers, antiseizure medicines, beta blockers, calcium channel blockers and the tricyclic drugs.

Once the migraine has started, treatment of menstrual migraines doesn't differ from treatment of regular migraines. Many women respond well to the standard medications, in c luding prompt use of an NSAID or prescription drugs such as the triptans (Amerge, Imitrex, other brands).

Many women find menstruation a pain. With these measures, you can prevent migraines from magnifying the distress.

Copyright 2007 the President and Fellows of Harvard College. Developed by Harvard Health Publications (www.health.harvard.edu). Distributed by UFS. Submit questions to harvard_ adviser@hms.harvard. edu.