1. Wash the Skin Gently With Soap and Water
Sumac rash is caused by urushiol oil, which produces an allergic reaction when it touches the skin. Wash the area using soap and warm water in order to get it off. If you have any anti-poison sumac medication, apply it as well. The sooner you do so, the better--within 30 minutes of being exposed to the oil if possible. Pay careful attention to your hands and fingers, which are the biggest culprits when spreading the sumac rash. Scrub under your fingernails with a brush, and wash any clothes that may have been exposed to the oil with hot water.
2. Stay Cool
Heat and sweat can aggravate the rash. Keep your skin cool by staying indoors and near air conditioning. You can also apply a cold compress to the rash directly. Soak a washcloth in ice-cold water and wrap it around crushed ice cubes. Hold it gently but firmly against the rash for 10 or 15 minutes, taking care not to rub it excessively against the skin. As the washcloth warms up, re-soak it in cold water or wrap more ice cubes in it, and then reapply it to the rash as appropriate.
3. Apply Topical Lotions
Lotions such as calamine and hydrocortisone directly address the symptoms of a sumac rash, though they don't treat the urushiol oil causing it. They can help you better control the itching and blisters, however, which will keep you from scratching at the rash and prevent further spread of the oil.
4. Take a Colloidal Oatmeal Bath
Colloidal oatmeal (not to be confused with the kind you have for breakfast) is used to help moisturize the skin, and to relieve rashes and itching as well. Draw a lukewarm bath. Add 2 to 3 cups of colloidal oatmeal as water fills the tub, and then soak in it for 10 to 15 minutes. Take care when you step out of the bath because the mixture can be slippery. Also be sure to blot yourself dry gently rather than rubbing with the towel, which could aggravate the rash.
5. Ask About Prescription Medication
In serious cases of sumac poisoning, a doctor can prescribe medicines that will help. Oral or injected steroids are often used to treat the rash, especially if it appears on your face or between your legs. A doctor may also prescribe antihistamines if topical medicines aren't working. Prescription medication is usually used only after other treatments have failed, and you should always speak to a doctor before taking these meds.
