Feverfew, a common perennial known to gardeners for its feathery foliage and aromatic blossoms, has been used as a botanical medicine since a.d. 78. The herb earned its name because it was commonly used to lower fever, but today, it’s more likely to be used by herbalists as a headache cure.

Some good evidence of feverfew’s headache-healing powers emerged in the mid-1980s during a study at the City of London Migraine Clinic. All of the people included in the study were accustomed to taking crushed feverfew leaves for their headaches, but researchers wanted to find out scientifically whether the cure worked as well as people claimed.

To test its effectiveness, one group was given capsules of pulverized feverfew leaves and another was given capsules that looked exactly the same but contained no feverfew (placebos). Neither group knew what they were taking. The people in the placebo group experienced a return of their headaches, while those taking the real thing did not. The feverfew was apparently doing its job.

After the study was published in 1985, feverfew emerged from the obscurity of the garden and into the limelight of botanical healing.

"I use it 100 percent of the time with my patients for migraines because it usually works," says Jennifer Brett, N.D., a naturopathic doctor in Stratford, Connecticut. "It’s a good alternative for people who have tried everything else."

The modern view of this herb is fairly close to that of sixteenth-century herbalist John Gerard. In 1597, Gerard recommended this member of the chrysanthemum family to "them that are giddie in the head" and suggested placing a poultice of the leaves on an aching noggin.

Ingesting rather than wearing the herb is the recommended course of treatment today, but it’s clear that the early healers were on to something, says Steven Dentali, Ph.D., a natural products chemist with Dentali Associates in Troutdale, Oregon, and a member of the advisory board of the American Botanical Council. "This is really a case where the folk use coincided with the science," he says. "Feverfew appears to be a good alternative to the drugs now being used for migraines."

In previous centuries, feverfew wasn’t just for headaches. Herbalists recommended it to relieve menstrual pain, expel the placenta after birth, treat arthritis, and break fevers. The common name is derived from febrifugia, which is Latin for "fever reducer."

"It does work for reducing fevers, but probably no one really uses it for that anymore," says Dr. Brett.

Just how feverfew works, scientists aren’t certain. The leaves—the medicinal parts of the plant—are rich in parthenolide, a compound that makes the walls of the blood vessels in the brain less reactive to substances that cause them to contract and dilate. That’s how migraines begin. The opening and closing of blood vessels may set off pain nerves and inflame the smooth muscles that line the blood vessels, says Alison Lee, M.D., a pain-management specialist and medical director of Barefoot Doctors, an alternative medicine practice in Ann Arbor, Michigan.