A tincture of its blossoms doubles as an insect repellent. It was once thought to be an antidote for overindulgence in opium. Feverfew appears to be an inhibitor of prostaglandin synthesis. Aqueous extracts prevent the release of arachidonic acid and inhibit aggregation of platelets. Extracts are also potent inhibitors of serotonin, inhibit phagocytosis, inhibit the deposition of platelets on collagen surfaces, exhibit antithrombotic potential, and inhibit mast cell release of histamine.
Adverse effects are usually mild.
One study of patients who stopped feverfew after taking it for several years experienced anxiety, migraine symptoms, and poor sleep patterns. Feverfew can cause inflammation of the oral mucosa and tongue with lip swelling and loss of taste. Do not give to children under the age of two. This herb may potentiate anticoagulants. Nature's Answer to Drugs .