Poison Ivy Rash

Poison ivy is a common poisonous plant that causes an itchy skin rash. Other rash-inducing poisonous plants include poison oak and poison sumac. These plants produce an oily sap that contains urushiol (pronounced yer-OO-shee-all), which causes an irritating, itchy allergic reaction. When you touch the poisonous plant or an object that’s been in contact with the plant’s oil, you develop an itchy rash on that area of your skin. This rash is a form of allergic contact dermatitis.

How common is a poison ivy rash?

Up to 90% of people who come into contact with poison ivy oil develop an itchy rash. You don’t have to be exposed to much: 50 micrograms (μg) of urushiol — an amount smaller than a grain of salt — is enough to cause a reaction. You can become susceptible to a poison ivy rash at any time in your life, even if you never reacted to it in the past.

Who might get a poison ivy rash?

Nearly everyone who touches urushiol gets a poison ivy rash. You’re more likely to come into contact with a poisonous plant if you’re a:

• Camper or hiker.
• Farmer or gardener.
• Groundskeeper or landscaper.
• Forestry worker.
• Forest firefighter.
• House painter.
• Roofer.

What do poisonous plants look like?

Poisonous plants grow everywhere in the United States except Hawaii and Alaska. Each type has a distinctive appearance.

What does poison ivy look like?

If you’re wondering how to identify poison ivy, look at its leaves. Each leaf of the poison ivy plant has three leaflets. A popular saying is, “leaves of three, let them be.” Poison ivy leaves turn reddish in the spring, green in the summer and yellow, orange or red in the fall.

Poison ivy grows as a shrub or a vine. A poison ivy vine is hairy and ropelike. Eastern U.S. poison ivy typically grows as a vine. Western U.S. poison ivy normally grows low to the ground as a shrub. Poison ivy does not have thorns. A poison ivy shrub may have white berries.

What does poison oak look like?

Poison oak leaves have three leaflets like poison ivy but with rounded tips. The undersides of the leaves are fuzzy and lighter in color than the top.

Poison oak typically grows as a shrub in the Eastern and Southern U.S. The shrub sometimes has white or yellow berries. Poison oak grows more commonly as a vine in the Western U.S.

What does poison sumac look like?

Each leaf of a poison sumac plant has clusters of seven to 13 smooth leaflets arranged in pairs. Poison sumac thrives in wet, swampy regions in the Northeast, Midwest and parts of the southeast U.S.

A full-grown poison sumac tree can get up to 20 feet tall. This tall tree has drooping clusters of pale yellow, cream-colored or green berries. Nonpoisonous sumacs have red, upright berries. Contact with nonpoisonous sumacs won’t cause an allergic rash.