DefinitionBy Mayo Clinic Staff
Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oil is in the leaves, stems and roots of poison ivy, poison oak and poison sumac.
Wash your skin right away if you come into contact with this oil, unless you know you're not sensitive to it. Washing off the oil may reduce your chances of getting a poison ivy rash. If you develop a rash, it can be very itchy and last for weeks.
You can treat mild cases of poison ivy rash at home with soothing lotions and cool baths. You may need prescription medication for a rash that's severe or widespread — especially if it's on your face or genitals.
Aug. 11, 2015
- AskMayoExpert. Contact dermatitis. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
- Bolognia JL, et al., eds. Irritant and allergic contact dermatitis, occupational dermatoses and dermatoses due to plants. In: Dermatology Essentials. Philadelphia, Pa.: Elsevier; 2014. http://www.clinicalkey.com. Accessed June 15, 2015.
- Wolff K, et al. Contact dermatitis. In: Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology. 7th ed. New York, N.Y.: The McGraw-Hill Companies; 2013. http://www.accessmedicine.com. Accessed June 15, 2015.
- Prok L, et al. Poison ivy (Toxicodendron) dermatitis. http://www.uptodate.com/home. Accessed June 16, 2015.
- Poisonous plants. National Institute for Occupational Safety and Health. Centers for Disease Control and Prevention. http://www.cdc.gov/niosh/topics/plants. Accessed June 15, 2015.
- Outsmarting poison ivy and other poisonous plants. U.S. Food and Drug Administration. http://www.fda.gov/forconsumers/consumerupdates/ucm049342.htm. Accessed June 15, 2015.
- AskMayoExpert. Poison ivy rash (adult and pediatric). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
- Patient education: Poison ivy. American Academy of Family Physicians. http://www.clinicalkey.com. Accessed June 15, 2015.
- Poison ivy. Nursing. 2014;6:47.
- Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. July 10, 2015.