In most people, contact with the oils from poison ivy, poison oak and poison sumac causes an allergic reaction. The area becomes inflamed, burns, itches, redness and blisters usually occur. This reaction is a form of contact dermatitis, a condition caused when an allergen that comes into direct contact with the skin.
Poison ivy is found more often in the eastern part of the country, while poison oak is more common in the southeastern part of the United States.
The poison ivy, poison oak and poison sumac plants all secrete urushiol, a substance that often irritates human skin. When you touch the leaves of these plants, some of the urushiol may absorb into your skin and cause a reaction even if it is only a small amount. Because urushiol does not dry, this sticky substance easily attaches to the skin, clothing, tools, equipment or a pet's fur.
People can develop a rash from:
The rash caused by these plants is not contagious because it does not contain the urushiol. Additionally, you cannot contract poison ivy, poison oak and poison sumac from another person unless the urushiol remains on the skin or clothing.
Usually, poison ivy, poison oak and poison sumac sufferers will exhibit some of these signs:
After exposure to one of these plants, the rash usually appears one to two days later and will clear up on its own in 14 to 21 days. If the itching becomes bothersome, you can try oatmeal baths, over-the-counter antihistamines and hydrocortisone creams. In severe cases or if the rash has become widespread, your doctor may recommend a prescription topical or an oral steroid.
The best defense against poison ivy, poison oak and poison sumac is to avoid coming in contact with these plants. Follow these suggestions: