Feverfew
Feverfew (Tanacetum parthenium) is a common
European composite herb with daisylike white flowers now widely naturalized in
the United States. While its name (a corrupted version of the Latin febrifugia) indi-cates a long history in
herb lore, feverfew’s current pop-ularity is due to its use in the prevention
and treatment of migraines. Feverfew has also been used for rheuma-toid
arthritis and numerous other conditions with far less substantiation. The
leaves contain sesquiterpene lactones, including parthenolide, which is thought to be the most active and important
ingredient. Feverfew preparations are frequently standardized for partheno-lide
content, which can vary substantially depending on time of harvest (levels drop
after seeds form) and other factors. Most studies have used feverfew
standardized to 0.6 to 0.7% parthenolide; the value of leaves con-taining less
than 0.2% parthenolide is questionable.
Parthenolide inhibits serotonin release, an action that is thought to be a likely source of its
effectiveness in mi-graine. Extracts have also been shown to reduce the
production of prostaglandins (another possible mecha-nism) and leukotrienes.
Interestingly, melatonin has been
identified in feverfew, a possibly significant obser-vation, since chronic
migraines have been associated with low melatonin levels.
At least three studies have
demonstrated that feverfew (dried leaf, not extract) can reduce the frequency
and severity of migraine headaches, although one study failed to find any
significant difference from placebo. Pro-phylaxis appears to be more effective
than acute treat-ment. There is also a consensus that feverfew is probably less
effective than conventional migraine prophylaxis, al-though it may have a role
as a second-line option. Although feverfew has also been used for rheumatism,
it has never been verified to be effective in clinical trials.
Although feverfew appears
generally safe in nonpreg-nant adults, the use of fresh leaves has caused mouth ir-ritation and even ulceration.
This is far less likely to occur when the herb is encapsulated. Allergic reactions (contact dermatitis)
have occurred with topical use in sensitized individuals, and ingestion may
also produce allergic reactions in people with preexisting allergies to members
of the Compositae family. Feverfew has caused contractions in term pregnancy
and has been implicated in cattle abortions and so should be avoided in
preg-nancy and lactation. A feverfew
withdrawal syndrome consisting of joint pain and muscle stiffness may occur
following abrupt discontinuation. Theoretically, because of its
antiprostaglandin effects, feverfew should not be coadministered with anticoagulants or antiplatelet drugs.
For migraine prophylaxis: 50 to 125 mg per day with food, preferably in capsule form to
prevent mouth irritation.
Feverfew may be considered as
an alternative migraine prophylaxis regimen in patients failing
to respond to conventional therapy.
It has not been shown to be ef-fective for rheumatoid arthritis. There is
insufficient ev-idence to support its use in other conditions.
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