Feverfew (Tanacetum parthenium; syn. Chrysanthemum parthenium (L.) Pers., Pyrethrum parthenium Sm.) is a traditional medicinal herb which is found in many old gardens, and is also occasionally grown for ornament. The plant grows into a small bush up to around 46 cm (18 in) high with citrus-scented leaves, and is covered by flowers reminiscent of daisies. It spreads rapidly, and they will cover a wide area after a few years. It is also commonly seen in the literature by its synonyms, Chrysanthemum parthenium (L.) Bernh. and Pyrethrum parthenium (L.) Sm.
Feverfew was native to Eurasia; specifically the Balkan Peninsula, Anatolia and the Caucasus, but cultivation has spread it around the world and it is now also found in Europe, the Mediterranean, North America and Chile.
Though its earliest medicinal use is unknown, it was documented in the first century (AD) as an anti-inflammatory by the Greek herbalist physician Dioscorides.
The word "feverfew" derives from the Latin word febrifugia, meaning "fever reducer." The plant has been used as a herbal treatment to reduce fever and to treat headaches, arthritis and digestive problems, though scientific evidence does not support anything beyond a placebo effect.
The active ingredients in feverfew include parthenolide and tanetin. There has been some scientific interest in parthenolide, which has been shown to induce apoptosis in some cancer cell lines in vitro and potentially to target cancer stem cells. There are no published studies of parthenolide or feverfew in humans with cancer. The parthenolide content of commercially available feverfew supplements varies substantially, by over 40-fold, despite labeling claims of "standardization". A study found that the actual parthenolide content of these supplements bore little resemblance to the content claimed on the product label.
Long-term use of feverfew followed by abrupt discontinuation may induce a withdrawal syndrome featuring rebound headaches and muscle and joint pains. Feverfew can cause allergic reactions, including contact dermatitis. Other side effects have included gastrointestinal upset such as nausea, vomiting, abdominal pain, diarrhea, and flatulence. When the herb is chewed or taken orally it can cause mouth ulcers and swelling and numbness of the mouth.
Feverfew should not be taken by pregnant women. It may interact with blood thinners and increase the risk of bleeding, and may also interact with a variety of medications metabolized by the liver.