Petasites hybridus, also known as thebutterbur, is a herbaceous perennialflowering plant in the familyAsteraceae that is native toEurope and northernAsia.^[1]

Petasites hybridus
Inflorescence
Foliage
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Tribe:	Senecioneae
Genus:	Petasites
Species:	P. hybridus
Binomial name
Petasites hybridus (L.)G.Gaertn.,B.Mey. &Scherb.
Synonyms[1][2]
Cineraria hybrida(L.) Bernh. Tussilago hybridaL. Tussilago petasitesL. Petasites officinalisL. Petasites ovatusL. Petasites vulgarisDesf.

Although used over centuries intraditional medicine to treat various disorders, there are no approved medical uses, but it is sold as adietary supplement.^[3][4] Concerns about the potential toxic effects ofpyrrolizidine alkaloids in butterbur limit its use in human and animal studies.^[4][5]

Butterbur may have derived from the use of leaves to wrap butter centuries ago.^[4] It is also calledbog rhubarb,Devil's hat, andpestilence wort.^{[citation needed]}

The species isdioecious, the male and female flowers being borne on separate plants. In Britain, the male flowers are widespread, but the female flowers have a restricted distribution in northern and central England.^[6]: 810

Theflowers are produced in the early spring, before theleaves appear. They are pale pink, with severalinflorescences clustered on a 5–20 cm (2–8 in) stem. The leaves are large, on stout 80–120 cm (31–47 in) tall stems, round, with a diameter of 40–70 cm (16–28 in) with petioles up to 1.5 m (4 ft 11 in).

It is native to central Europe, extending from the British Isles to theCaucasus, and from southern Italy to southernScandinavia.^[7] It is present as an introduced species in North America.^[2] In the British Isles, female plants are rarely found outside central and northern England and the species may be naturalized as clonal populations outside this area,^[6]: 810 propagating via rhizome fragments. The preferred habitats are moist, fertile soils often by rivers, streams, and inwet meadows.^[8]

As there are no approved clinical uses of butterbur or itsextracts, preparations are sold in some countries as a dietary supplement.^[3][4] There is no evidence that butterbur is useful for treatingskin allergies,bronchitis,urinary tract infections,asthma, or other disorders.^[3]

Although some preliminary studies indicate that butterbur may reduce the frequency ofmigraine headaches in adults and children, clinicalneurology associations do not recommend it because of concerns of possibleliver toxicity.^[3][4]

Although there have been studies of butterbur root or leaf extracts as possible therapies for symptoms of hay fever (allergic rhinitis), the results were insufficient to determine effectiveness and safety.^[3][4][9]

Petasites hybridusleaves were used inAustrian andCzech traditional medicine internally (as tea or cold maceration in ethanol) and externally (as compresses or maceration in vinegar) for treatment of infections, fever, flu, colds, hay-fever, and allergies.^[10]

Petasites hybridus containssenecionine and other toxicpyrrolizidine alkaloids in its leaves and roots.^[4][5] Also present are thesesquiterpeneesters –petasin, isopetasin, and neopetasin.^[4]

Butterburextracts have been found to contain hepatotoxic pyrrolizidine alkaloids at the retail level.^[3][4][5] These extracts are not recommended during pregnancy or breastfeeding.^[4]

The adverse effects of butterbur reported in clinical trials include mainly gastrointestinal problems, such as nausea, flatulence, and belching.^[4] In 2015, the American Academy of Neurology withdrew its original endorsement of butterbur due to safety concerns.^[11]

Long-term health effects and interaction of butterbur with other drugs have not been well documented. However, it can theoretically interact with certain blood pressure and heart medications, as well as with drugs that can induce a liverenzyme calledCYP3A4.^[4] Prior cases of liver damage have been reported from people taking butterbur, with cases varying inadverse effects fromcholestasis andinflammation to liver failure.^[4][5][12]

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