Poison ivy

Skin | General Practice | Poison ivy (Disease)


Toxicodendron radicans, better known as poison ivy (older synonyms are Rhus toxicodendron and Rhus radicans), is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within thesap of the plant that causes an itching, or sometimes painful rash in most people who touch it.

Causes and Risk factors

Urushiol binds to the skin on contact, where it causes severe itching that develops into reddish coloured inflammation or non-coloured bumps, and then blistering. The reaction usually develops 12 to 48 hours after exposure and can last up to eight weeks.

The severity of the rash is dependent on the amount of urushiol that gets on your skin. In severe cases, new areas of rash may break out several days or more after initial exposure. This may seem like the rash is spreading. But its more likely due to the rate at which your skin absorbed the urushiol.

Your skin must come in direct contact with the plants oil to be affected. Blister fluid from scratching doesnt spread the rash, but germs under your fingernails can cause a secondary bacterial infection.

Diagnosis and Treatment

These lesions may be treated with Calamine lotion, Burows solution compresses or baths to relieve discomfort, though recent studies have shown some traditional medicines to be ineffective. Over-the-counter products to ease itching—or simply oatmeal baths and baking soda—are now recommended by dermatologists for the treatment of poison ivy. ...