Poison Ivy, Oak and Sumac
About half the American population is allergic to leaves containing urushiol oil. The leaves of poison ivy, oak and sumac all contain this potent oil. Only 1 nanogram (billionth of a gram) of urushiol is needed to cause a rash. If the sticky, resin-like substance remains on your hands, it can spread to others, but the rash it causes won’t spread to other parts of your body or contaminate another person.
Don’t rely on the old saying, “Leaves of three, let them be.” While poison ivy and oak do have only three leaves, poison sumac has 7-13 leaves on a branch. Just because a poison ivy, oak or sumac plant looks dead, don’t assume it is safe. Urushiol can stay active on any surface, even dead plants, for 1 to 5 years.
Avoid contact with a plant, if possible. If you’ve come in contact with a plant, start washing everything – skin, clothes, watchband, shoes, shoelaces – that may have touched the plant with soap, detergent or rubbing alcohol. If done within 15 minutes after contact, you may not even get a rash.
If you do get a rash, it can last from one to four weeks. To treat intense itching, your doctor may recommend antihistamines and drying agents like calamine lotions. Frequent applications of topical anesthetics such as method, benzocaine and paramoxine work well to numb the itchy rash. Several hours of relief may come from soaking in baking soda, commercial oatmeal or colloidal baths for 15 to 30 minutes. Applying hydrocortisone creams or sprays several times a day may reduce inflammation and swelling.
See a doctor if facial or genital swelling occur or itching is not calmed by over-the-counter medicines. Be alert to signs of infection: pain, tenderness, growing redness around the rash or pus. Clear or slightly yellow transparent fluid is common from poison ivy blisters and is not a sign of infection.