Tanacetum parthenium, known as feverfew,[1] is a flowering plant in the daisy family, Asteraceae. It may be grown as an ornament, and may be identified by its synonyms, Chrysanthemum parthenium and Pyrethrum parthenium.

The plant is a herbaceous perennial that grows into a small bush,[2] up to 70 cm (28 in) high, with pungently-scented leaves. The leaves are light yellowish green, variously pinnatifid. The conspicuous daisy-like flowers are up to .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}20 millimetres (3⁄4 in) across, borne in lax corymbs. The outer, ray florets have white ligules and the inner, disc florets are yellow and tubular. It spreads rapidly by seed, and will cover a wide area after a few years.[3][4]

Feverfew is native to Eurasia, specifically the Balkan Peninsula, Anatolia, and the Caucasus, but cultivation has spread it around the world and the rest of Europe, North America, and Chile.[2][5]

A perennial herb, it should be planted in full sun, 38 to 46 cm (15–18 in) apart, and cut back to the ground in the autumn. It grows up to 70 cm (28 in) tall. It is hardy to USDA zone 5 (−30 °C (−22 °F)). Outside of its native range, it may become an invasive weed.[6]

In traditional medicine, feverfew has been used to treat headache, but there is no confirmed scientific evidence that it has such an effect.[2][7][8] Feverfew contains parthenolide, which is under basic research to assess its properties on cancer.[8] Feverfew is registered as a traditional herbal medicine in the Nordic countries under the brand name Glitinum. Only powdered feverfew is approved in the European Union herbal monograph.[9]

The parthenolide content of commercially available feverfew supplements varies substantially (by more than 40-fold) despite labeling claims of "standardization".[10]

Long-term use of feverfew followed by abrupt discontinuation may induce a withdrawal syndrome featuring rebound headaches and muscle and joint pains.[8] Feverfew may cause allergic reactions in those allergic to the daisy family, including contact dermatitis or swelling and numbness of the mouth.[8] Other side effects have included gastrointestinal upset such as mild nausea, vomiting, abdominal pain, diarrhea, and flatulence, which are, fortunately mild and transient.[8] When the herb is chewed or taken orally it may cause mouth ulcers.[8] Feverfew should not be taken by pregnant women.[8] It may interact with blood thinners and increase the risk of bleeding, and also may interact with a variety of medications metabolized by the liver.[8]

The word feverfew derives from the Latin word febrifugia, meaning 'fever reducer',[11] although it no longer is considered useful for that purpose.

Although its earliest medicinal use is unknown, it was documented in the 1st century CE as an anti-inflammatory by the Greek herbalist physician Dioscorides.[12]