Feverfew contains a range of compounds known as sesquiterpene lactones. Over 85% of these are a compound called parthenolide. In test tube studies, parthenolide prevents excessive clumping of platelets and inhibits the release of certain chemicals, including serotonin and some inflammatory mediators.
Although this herb has long been used in migraine prophylaxis, confirmed by clinical studies, the precise mechanism of the action is not yet fully understood. It is thought that the prophylactic action is due to serotonin (5-HT) inhibition, possibly via the neutralization of sulphydryl groups on specific enzymes that are fundamental to platelet aggregation and secretion.
Abnormal platelet behaviour with the release of 5-HT has been implicated in migraine. Parthenolide also interferes with both the contractile and relaxant mechanisms in blood vessels. Many of the patients involved in the clinical trials for migraine prophylaxis also reported that feverfew helped their depression. It helps ease tinnitus and dizziness, and allays nausea and vomiting.
Feverfew has long been reputed to help relieve arthritis, particularly in the painful active inflammatory stage. The sesquiterpene lactones, and particularly parthenolide, have been shown to inhibit human blood platelet aggregation and secretory activity in platelets and polymorphonuclear leucocytes (increased secretion is a feature of rheumatoid arthritis). However, a double-blind, placebo-controlled study over six weeks on 40 females with rheumatoid arthritis showed no beneficial effects.
Feverfew has been used in the treatment of dysmenorrhoea and sluggish menstrual flow, and an infusion may be taken to cleanse the uterus after childbirth. Antimicrobial properties against Gram-positive bacteria, yeasts and filamentous fungi in vitro have been documented for parthenolide; Gram-negative bacteria were not affected.
Herbal products in capsules or tablets providing at least 250mcg of parthenolide per day may be taken. It may take more than a month of use before benefits are noticed.
The fresh leaves can cause mouth ulceration or gastric disturbance so it is recommended that those taking the fresh leaf for migraine prophylaxis should take it with some bread. Its use is contraindicated in pregnancy due to its stimulating action on the uterus.