DermNet provides Google Translate, a free machine translation service. Note that this may not provide an exact translation in all languages


Cow parsnip

Author: Hon A/Prof Marius Rademaker, Dermatologist, Hamilton, New Zealand,1999.

Common name: Cow parsnip or hogweed
Botanical name: Heracleum spondylium
Family: It belongs to the Apiaceae family (or Umbelliferae), which has over 2500 species in 275 genera. These include common herbs such as giant hogweed, anise, carrot, celery, coriander, dill, fennel, parsley, and parsnip, as well as the highly toxic hemlocks.
Origin: Native to North  America.
Description: The Apiaceae family are characterised by alternate leaves, which widen at the base into a sheath that clasps the stem. The stems are often furrowed with the flowers usually compound, almost always concentrated in flat-topped umbels. The flowers have 5 petals, usually uneven, and 5 stamens. Seeds and fruit form below where the petals and stamen originate Some parts of the plant usually have a strong aroma, due primarily to various oils produced by the plant.

Uses: Cow parsnip often grows in moist meadows, and along the borders of fields, and near ditches. Traditionally the young leaf stalks and stems were eaten like stewed celery. The leaves may be dried, burned and the ashes used as a salt substitute. Native Americans of the northern US ate the peeled stalks raw or cooked. The blossoms were steeped in oil and rubbed on the body to keep off flies and mosquitoes.
Allergens: Furocoumarins (psoralens) including bergapten, isobergapten, sphondin, isopimpinellin and pimpinellin.
Allergy: Unfortunately, the umbilliferae contain furano-coumarins which, when exposed to sunlight, cause significant phototoxic reactions (photosensitivity). One of the more common skin reactions to cow parsnip/hogweed, is the ‘weed eaters’ or ‘strimmers’ dermatitis. When string trimmers are used to clear long grass, components of weeds are usually mulched and scattered in all directions, often coating the legs and arms of the operator. The sap of the plants then gets on the skin, and, when exposed to sunlight, gives rise to a very characteristic rash (see photo) which may persist for many months.

String trimmers dermatitis

Cross reactions:  
Other information: Heracleum, is from the Latin, Herâclêus, "of or belonging to Hercules". The common name comes from its perceived similarity to the parsnip, and its appeal to cattle.
Patch test:  



  • Oakley AM, Ive FA, Harrison MA. String trimmer's dermatitis. J Soc Occup Med. 1986 Winter;36(4):143-4.
  • McGovern TW, Barkley TM. Related Articles. Botanical briefs: giant hogweed; Heracleum mantegazzianum Sommier & Levier. Cutis. 2000 Feb;65(2):71-2.
  • Jaspersen-Schib R, Theus L, Guirguis-Oeschger M, Gossweiler B, Meier-Abt PJ. [Serious plant poisonings in Switzerland 1966-1994. Case analysis from the Swiss Toxicology Information Center]. Schweiz Med Wochenschr. 1996 Jun 22;126(25):1085-98. German.
  • Lagey K, Duinslaeger L, Vanderkelen A. Burns induced by plants. Burns 1995 Nov;21(7):542-3.
  • Ippen H. [Phytophotodermatitis caused by plant trimming (edger's rash)]. Derm Beruf Umwelt. 1990 Nov-Dec;38(6):190-2. German.
  • Tiedemann A, Schultze H. [Bullous photodermatitis following contact with the stem sap of the giant bear claw (Heracleum mantegazzianum)]. Z Arztl Fortbild (Jena). 1987;81(5):235-6. German.
  • Rogov VD. [Acute bullous dermatitis developing after contact with cow parsnip (Heracleum)]. Vestn Dermatol Venerol. 1985 Nov;(11):58-9. Russian.
  • Patkova V. [Dermatitis due to cowparsnip (Heracleum giganteum)]. Cesk Pediatr. 1984 Feb;39(2):118-9. Czech.
  • Ippen H. [Photodermatitis bullosa generalisata]. Derm Beruf Umwelt. 1984;32(4):134-7. German.
  • Kavli G, Midelfart K, Raa J, Volden G. Phototoxicity from furocoumarins (psoralens) of Heracleum laciniatum in a patient with vitiligo. Action spectrum studies on bergapten, pimpinellin, angelicin and sphondin. Contact Dermatitis. 1983 Sep;9(5):364-6.
  • Kavli G, Midelfart K, Volden G, Krokan H. Photochemical reactions of Heracleum laciniatum. Influence of dimethyl sulphoxide and corticosteroids. Br J Dermatol. 1983 Jul;109 Suppl 25:137-40.
  • Kavli G, Raa J, Johnson BE, Volden G, Haugsbo S. Furocoumarins of Heracleum laciniatum: isolation, phototoxicity, absorption and action spectra studies. Contact Dermatitis. 1983 Jul;9(4):257-62.
  • Kavli G, Volden G, Midelfart K, Krokan H, Prytz JO, Haugsbo S. In vivo and in vitro phototoxicity of different parts of Heracleum laciniatum. Contact Dermatitis. 1983 Jul;9(4):269-73.
  • Kavli G, Midelfart GV, Haugsbo S, Prytz JO. Phototoxicity of Heracleum laciniatum. Case reports and experimental studies. Contact Dermatitis. 1983 Jan;9(1):27-32.
  • Ippen H. [Phototoxic reaction to figs]. Hautarzt. 1982 Jun;33(6):337-9. German.
  • Kavli G, Volden G, Raa J. Accidental induction of photocontact allergy to Heracleum laciniatum. Acta Derm Venereol. 1982;62(5):435-8.
  • Weimarck G, Nilsson E. Phototoxicity in Heracleum sphondylium. Planta Med. 1980 Feb;38(2):97-111.
  • Prinz VL, Kostler H. [Report on 3 cases of toxic phytophotodermatitis due to Heracleum mantegazzianum (giant cow parsnip)]. Dermatol Monatsschr. 1976 Nov;162(11):881-6. German.
  • Kumar R, Banerjee SK, Handa KL. Coumarins of Heracleum canescens and Heracleum pinnatum. Sources for dermal photosensitizing agents. Planta Med. 1976 Nov;30(3):291-4.
  • Camm E, Buck HW, Mitchell JC. Phytophotodermatitis from Heracleum mantegazzianum. Contact Dermatitis. 1976 Apr;2(2):68-72.
  • Qadripur SA, Grunder K. [Case contribution on a group affliction with photodermatitis bullosa striata pratensis (Oppenheim)]. Hautarzt. 1975 Sep;26(9):495-7. German.
  • Fensom DS, Davidson HR. Micro-injection of 14C-sucrose into single living sieve tubes of Heracleum. Nature. 1970 Aug 22;227(260):857-8.
  • Jain SR. Investigations on the essential oil of Heracleum mantegassianum L. Planta Med. 1969 Aug;17(3):230-5.
  • Lovell CR.1993, Plants and the Skin, Blackwell, Oxford.
  • Mitchell JC, Rook A, 1979, Botanical Dermatology, Plants and Plant products injurious to the skin, Greengrass, Vancouver.


Related information

Sign up to the newsletter