Poison sumac is one of a trio of plants, including poison ivy and poison oak, that cause a rash if a person is allergic to them. The plants release urushiol oil, a substance found in the stems, leaves, fruit and leaves, when they are bruised or damaged. Some individuals do not react to urushiol oil, but most of the population is sensitive to it. An intensely itchy rash may appear within 24 to 72 hours. Without treatment, the rash normally will subside within several weeks. See your doctor if the rash spreads to your eyes, mouth or genitals -- further treatment may be required.
Washing the entire body with soap and water within 10 to 15 minutes of contact with poison sumac may prevent a rash by removing the urushiol oil from the body, which adds that commercial products such as Goop or Tecnu may be even more effective. Shoes, clothing, tools and anything else that came into contact with the plant should be cleaned with alcohol and water to prevent repeat contact with the skin. If left on objects, urushiol oil can cause an allergic reaction years later.
If a rash and blisters develops, the patient should avoid scratching the skin because organisms can enter the broken areas and cause an infection. To soothe the itching and reduce swelling, the individual can apply cool compresses to the skin or soak in a cool bath several times a day. Oatmeal or baking soda added to the bath water may be helpful. Burows solution, also called aluminum acetate solution, may be applied to the blistered areas two or three times a day for 20 minutes. To prepare the treatment, one or two over-the-counter Dome-Boro tablets should be mixed in 1 pt. of water, then compresses soaked in the solution should be applied to the affected skin.
Over-the-counter medications can help to reduce swelling and itching. Calamine lotion or corticosteroid creams may be applied to the skin. Diphenhydramine, an antihistamine, can be given by mouth to relieve itching and help the people to sleep. Zinc oxide can help to protect the skin and dry the blisters. Prescription medications, including antibiotics for an infection and corticosteroids for widespread rashes, may be needed if home remedies are not effective.