What is Rhus Dermatitis?

Rhus dermatitis is a type of allergic skin reaction that occurs when a person comes into contact with oils secreted by certain types of plants. The most common sources of rhus dermatitis are poison oak, poison ivy, and poison sumac, though other plants from the Rhus or Toxicodendron genera can also cause contact rashes. An individual is likely to experience severe skin irritation, inflammation, itching, and blistering that can last for several days. Healing time can usually be shortened by keeping the affected area of the skin clean, and by applying topical cream to relieve itching and irritation.

Plants like poison ivy and poison sumac produce an oil called urushiol that is highly irritating to the skin of most people. An individual who comes into direct contact with the oil or picks up traces from clothing or camping supplies is likely to experience rhus dermatitis. Urushiol on the skin triggers the immune system to release antibodies to attack the foreign particles. It is the body's response, rather than the plant oil itself, that causes inflammation and other symptoms.

In most cases, the rash produced in rhus dermatitis first appears at the site of contact and spreads over time to affect a larger area of the body. Common symptoms include persistent itching, red streaks on the skin, and mild burning sensations. Over time, the skin can begin to blister and ooze a milky pus. Mild cases tend to clear up in about one week, but a person who is highly allergic or exposed to a large quantity of urushiol can experience symptoms for a month or longer without treatment.

Most instances of rhus dermatitis can be effectively treated at home. If a person knows that he or she has just touched a plant, a reaction can sometimes be deterred by washing the area with antibacterial soap and water. Once a rash appears, though, washing does not help to ease symptoms. Applying ice and lotion to the affected body part can help numb pain and relieve itching, and using over-the-counter hydrocortisone cream can lessen inflammation. A doctor should be contacted if the rash is not resolved by home treatments.

A physician typically can carefully inspect rhus dermatitis and determine the best way to treat it. Patients are often prescribed high-strength topical or oral antihistamines to reduce inflammation and itching symptoms. Steroid medications are administered to stop the immune system's response in severe cases. Doctors can also help people better understand the condition and learn how to prevent exposure and resulting rhus dermatitis in the future.