Poison sumac is less common but more toxic ... Treating the Rash: If a rash develops, over-the-counter treatments like calamine lotion, hydrocortisone cream, and antihistamines can help alleviate ...

Poison ivy, oak, and sumac rashes will heal on their own in about three weeks, and over-the-counter treatments can help relieve the symptoms. However, if the rash is more widespread or severe ...

and poison sumac are three of the most common causes of allergic contact dermatitis in the U.S. They all contain an oil called urushiol, which triggers an allergic reaction, usually an itchy rash.