Taxonomic class

Asteraceae

Common Trade Names

Feverfew, Feverfew Glyc, Feverfew Power, Tanacet

Common Forms

Available as capsules (pure leaf, 380 mg; leaf extract, 250 mg), liquid, and tablets. The leaves are commonly used to make infusions or teas.

Source

Feverfew, a plant from Europe naturalized in the United States and Canada, bears yellow-green leaves and yellow flowers from July to October. The leaves of the plant are usually dried or used fresh in teas and extracts. The most commonly cited botanical name is Chrysanthemum parthenium, synonymous with Tanacetum parthenium. Matricaria parthenium, Leucanthemum parthenium, and Pyrethrum parthenium are also used to refer to the plant.

Chemical Components

The leaves and flowering tops of feverfew contain many monoquiterpenes and sesquiterpenes as well as sesquiterpene lactones (chrysanthemolide, chrysanthemonin, 10-epi-canin, magnoliolide, and parthenolide), reynosin, santamarin, tanaparthins, and other compounds. Parthenolide may be absent or occur in variable amounts, depending on geographic and other variables. Interestingly, melatonin has been found in significant quantities in both the feverfew plant and commercial feverfew products. Fresh green feverfew leaf contains 2.45 mcg/g of melatonin, whereas the freeze-dried leaf contains 1.61 mcg/g of melatonin .

Actions

The main active ingredients are the sesquiterpene lactones, particularly parthenolide, which inhibits serotonin release by human platelets in vitro. This may be the mechanism of action for feverfew’s purported efficacy in treating migraine headaches . Parthenolide also inhibits serotonin release and has demonstrated significant cytostatic activity toward mouse fibrosarcoma (MN-1 1) and human lymphoma . Extracts of feverfew contain several chemicals that inhibit activation of polymorphonuclear leukocytes and the synthesis of prostaglandins and leukotrienes (by way of inhibition of the cyclooxygenase and 5-lipoxygenase pathways). In murine studies, anti-inflammatory and antinociceptive effects have been documented for both feverfew extract and parthenolide.

Reported uses

Although the initial enthusiasm for feverfew has waned, plant preparations are again becoming increasingly popular for use in migraine prophylaxis and as an antipyretic. A detailed and systematic review of all trials of feverfew for migraine prevention published before mid-1998 failed to find sufficient evidence to support the use of feverfew in this regard.

Feverfew is also claimed to be useful for treating asthma, insect bites, menstrual problems, threatened miscarriage, psoriasis, rheumatism, stomachache, and toothache. These uses have not been assessed in human trials.

Dosage

For migraine prophylaxis, 25 mg of freeze-dried leaf extract P.O. daily; 50 mg of leaf P.O. daily with food; or 50 to 200 mg of aerial parts of plant P.O. daily.

For migraine treatment, average dose of 543 mcg P.O. parthenolide daily.

Adverse Reactions

EENT: mouth ulcers (common with teas and whole-herb preparations).

Other: hypersensitivity reactions, post-feverfew syndrome (withdrawal syndrome characterized by moderate to severe pain, joint and muscle stiffness, and anxiety).

Interactions

None reported.

Contraindications And Precautions

Feverfew is contraindicated in pregnant or breast-feeding women.

Special considerations

Monitor for allergic reaction.

Monitor for mouth ulcers. Encourage the patient to exercise proper oral hygiene.

Feverfew potency is often based on the parthenolide content in the preparation, which is variable.

Instruct the patient not to withdraw the herb abruptly but to taper its use gradually because of the risk of post-feverfew syndrome.

Inform the patient that several other strategies for migraine treatment and prophylaxis exist and that they should be attempted before taking products with unknown benefits and risks.

Encourage the patient to promptly report unusual symptoms, such as mouth sores and skin ulcerations.

Commercial feverfew products are likely to contain small amounts of melatonin.

Points of Interest

The concentration of parthenolide in the leaves and flowering tops is highest during the summer, before the seeds are set, and drops rapidly thereafter. This has been offered as an explanation for the difference in parthenolide levels between brands of feverfew capsules and tablets.

The Health Protection Branch of the Canadian government has proposed a standard that formulations contain a minimum of 0.2% parthenolide.

Commentary

Although feverfew has been shown to be effective for migraine prophylaxis in at least two clinical trials, further studies are needed to define better dosage guidelines and specific drug interactions and mechanisms of action. For patients in whom standard drug therapy has failed, feverfew may be an agent that can prevent migraine attacks. Although standardized feverfew preparations with dosages based on free parthenolide content have the best experimental support, no consensus on use exists. The presence of melatonin in feverfew and other botanicals emphasizes the need for complete biochemical characterization of herbal medicinals.