Feverfew (Tanacetum parthenium) is a common bushy shrub found in most of Europe, North America, and South America.

The yellow-green leaves are citrus-scented, but the plant as a whole has a such a strong, bitter odor that bees avoid it. White-and-yellow flowers resembling small daisies bloom from July to October. These leaves and blossoms contain feverfew’s active ingredients.1

This attractive perennial stands about 18 inches tall and is easily grown from seed in pots, borders, or gardens, with little cultivation.

Background

Feverfew has been used as a medicinal herb for centuries,2 most often for menstrual-cramp relief and migraine prophylaxis.1

Estimates of migraine incidence in Western countries is as high as 9% of men and 25% of women.3 These numbers amount to a staggering 24 million Americans.4 Recent data calculate direct and indirect costs (medical care for patients and lost work for their employers) at a total of $24 billion.5

Many pharmacologic remedies exist for both prophylactic and abortive migraine therapy but few are completely effective, and all require prescriptions, rendering them more costly and less accessible for many patients than an herbal alternative.

Mechanism of action

Migraines are episodic, typically unilateral, throbbing head-aches. While their cause is still mysterious, researchers believe they develop when some signal triggers a massive release of inflammatory mediators, such as histamines, from cells in the cranial-nerve roots, particularly the trigeminal nerve.6

Since the 1980s, most interest in feverfew has been directed at migraine prophylaxis, or the prevention of this chemical release. Feverfew flowers and leaves contain sesquiterpene lactones, particularly parthenolide, which inhibits serotonin release by human platelets. This action and an inhibitory effect on the synthesis of leukotrienes and prostaglandins are be- lieved to explain the possible migraine prophylactic action.6

A Cochrane review of studies on feverfew for migraines found five small randomized, placebo-controlled trials involving a total of 343 patients.7 Only one of them used the International Headache Society (IHS) criteria for migraine definition.8 In all, four trials reported results slightly in favor of feverfew over placebo, and one found no statistical difference.7

A separate study of 57 patients with histories of severe migraines at least once a month found use of a daily standardized dose of feverfew reduced the incidence of migraine by 24% over placebo.9 And another trial of 72 patients randomized for eight months to one capsule of dried feverfew leaves daily or placebo showed a reduction in headache frequency compared with the placebo group.9 However, due to protocol inconsistencies, the statistical significance of this trial is questionable.

A larger trial of 170 migraine sufferers ran- domized patients to placebo or feverfew 6.25 mg taken orally three times daily in a standardized extract. Monthly attacks declined from an overall average of 4.76 by 1.9 in the treatment arm and by 1.3 attacks  in the placebo group.10

More recent studies are exploring feverfew’s possible anticancer properties. Some small in vitro and  phase 1 clinical trials indicate that a test dose of 4 mg of the parthenolide ingredient in feverfew is toxic to cancer cells. Researchers believe that the sesquiterpene lactones, specifically parthenolide, are responsible for resultant apoptosis in early tumor cells.11