Exposure to poison ivy, poison oak, or poison sumac plants results in an allergic reaction of the skin to the plant oil called urushiol.
Not everyone is allergic to urushiol. If the urushiol from the plant touches the skin of someone who is allergic to it, it starts a reaction that results in blisters. This reaction is known as an allergic contact dermatitis. The outbreak of the reaction starts at the spot on the skin where the urushiol touched it. Once the urushiol has been thoroughly washed off the skin, no further spread of the dermatitis can occur.
Original sites of contact may continue to break out with blisters over the next several days. Portions of the skin that had the most contact usually react first, followed by areas of skin that had less contact with the plant. This often gives people the incorrect impression that the dermatitis is contagious.
Symptoms of poison ivy, poison oak, or poison sumac dermatitis include red welts and blisters on exposed areas of skin. These areas may have burning and itching that ranges from mild to severe.
Skin contact with urushiol from poison ivy, poison oak, or poison sumac plants causes the allergic contact dermatitis.
To prevent an allergic reaction to urushiol, individuals should avoid contact with poison ivy, poison oak, or poison sumac plants. Long sleeves and long pants provide a barrier to the urushiol. It is also important to wash both the skin and clothing thoroughly after any potential contact. A skin cream is available for people who are especially sensitive to urushiol and cannot avoid the plants.
Often the person diagnoses the allergic contact dermatitis himself or herself by noticing the itchy blisters and recalling plant contact. Otherwise, the healthcare provider makes the diagnosis by examining the rash and asking about possible urushiol contact.
There are usually no long-term effects from exposure to poison ivy, poison oak, or poison sumac. Repeated bouts of the allergic contact dermatitis can become more severe. The allergic reaction may be particularly bothersome when it involves large areas of the skin surface, the face, or the mouth.
The allergic contact dermatitis can only be spread to other individuals if someone comes in contact with the urushiol on the person's skin before it has been washed off. Special care needs to be taken when handling clothing, jewelry, shoes, tools, or animals that have come into contact with any part of the plant. Contact with a person's blisters or fluid from broken blisters does not spread the dermatitis.
Treatments for poison ivy, poison oak, or poison sumac dermatitis range from home remedies to prescription medications. Common treatment measures include the following: cool compresses soaked with tap water, baking soda water, or Epsom salts to temporarily relieve symptomstepid baths in water containing products made from ground oatmealtopical corticosteroids, such as hydrocortisone, betamethasone dipropionate, or triamcinolone (i.e., Aritacort)oral or topical antihistamines such as diphenhydramine (i.e., Benadryl) to relieve itchingoral corticosteroids, such as prednisone or methylprednisolone (i.e., Medrol), for severe cases
If used for several days to weeks, oral corticosteroids may cause mood disturbance, increased appetite, increased blood pressure, elevated blood glucose, and bone or skin thinning. However, treatment for urushiol exposure should not be needed for long enough to cause these effects.
Recuperation from poison ivy, poison oak, or poison sumac dermatitis should occur in one to two weeks, although repeat occurrences occasionally happen with repeat exposure. Reexposure to urushiol may occur, for example, after handling camping gear, golf clubs, clothing, or pet fur that was originally in contact with the plant.
Any new or worsening symptoms should be reported to the healthcare provider.