Poison ivy is often identified by the saying "leaves of three let them be.” Generally poison ivy and poison oak have three leaflets per leaf with flowering branches on a single stem. Poison sumac, on the other hand, has five, seven and more leaflets per leaf that angle upward toward the top of the stem.
When the skin comes in direct contact with an irritating or allergy causing substance a contact dermatitis can occur. Exposure to poison ivy, poison oak or poison sumac causes more cases of contact dermatitis than any other plant. These plants contain a compound called urushiol, which is colorless oil that is found on the plant.
You can be exposed to urushiol by touching the sap or rubbing against the leaf of the toxic plant. This can occur at any time of the year. Other ways to be exposed are by touching something that has urushiol on it such as animal fur or garden tools, and breathing in the smoke after the toxic plants have been burned. Ginkgo fruit and the skin of mangos contain urushiol and produce similar symptoms of poison ivy dermatitis.
Fifty percent of people who come in contact with urushiol develop symptoms of poison ivy dermatitis. The most common symptoms are intense itching skin, swelling and redness. The symptoms usually develop within four hours to four days after exposure. Fluid filled blisters in a line or streak like pattern can develop. The symptoms are worse within 1 to 14 days but can develop up to 21 days later if one has never been exposed to urushiol in the past.
The blisters can occur in different locations at different times. This does not mean that the reaction is spreading from one part of the body to another. The fluid that leaks from the blisters does not spread the rash, and it is not contagious, however, urushiol can be carried under fingernails and on clothes and shoes and then be spread that way. If another person comes in contact with the urushiol he or she can develop the dermatitis.
Poison ivy dermatitis will usually resolve in 1 to 3 weeks without treatment. There are treatments that can help relieve the itching and discomfort of the dermatitis. These include adding oatmeal to a bath or applying cool wet compresses to the area. Also calamine lotion may help relieve the itching. Antihistamines do not relieve the itching caused by poison ivy dermatitis. Some antihistamines such as Benadryl will help with sleep. Steroid creams may be helpful if used during the first few days after symptoms appear. If you develop severe symptoms or the rash covers a large area or is on your face, call your doctor. You may need steroid pills or an injection.
The best way to prevent poison ivy dermatitis is to avoid the plants that cause it. They can irritate the skin year round even after they have died. Wear protective clothing with long sleeves and pants and heavy duty gloves when working in areas where these plants can be found. If you come in contact with one of these plants remove any contaminated clothing and gently wash your skin and under your fingernails with mild soap and water. Washing within 10 minutes of exposure can limit the likelihood and severity of the symptoms. If you have questions ask your family medical provider.