Poison Oak, Poison Ivy, Sumac

H. Farhadian, M.D., F.A.A.P., F.A.A.A.A.I.
Copyright© 2019, H. Farhadian, MD. All rights reserved.



During summer and fall, people go to parks and woods for recreation or a walk. While this is a good and healthy exercise, make sure that you will not have exposure to poison plants. The most common poisonous plants are from the "Toxicodendron" family. The most commonly known are poison oak, poison ivy and poison sumac. About 80 to 85 percent of Americans are allergic to these plants. Poison oak/ivy/sumac are native to northern and eastern America. Each grows well in California in woods and on hillside properties. They grow between 4-8 feet and can be found in vines, shrubs or climber form. The leaves are in different forms and shapes. Poison ivy leaves are oval shaped with small grooves and teeth. The leaves of poison oak have deeper grooves. However, they are all common for one thing, the arrangement of leaves... three leaves on one small branch. This is why it is known as the "Three Leafed Vine". These plants have bright red fruits in fall that make them easily recognizable.

These families of plants have a juice called oleoresin and the allergen that causes the skin reaction is called urushiol. The skin rash and allergic reaction that develops by contact with the plant is known as contact dermatitis. The itching and rash usually begin within 24-48 hours after exposure to the allergen (the substance that causes the allergy). The symptoms gradually become aggravated with development of blisters and excessive itching followed by crusting and scab formation. After one week, the skin lesion gradually improves and within 2-3 weeks complete recovery follows.

The exposure to the plant could be direct or indirect. For example, a dog could carry the allergen from the plant to a human. Treatment of exposure is to cleanse the skin by washing with warm water and soap immediately. After drying, apply cortisone cream. In many cases, this treatment is not adequate and the person should see his/her doctor or, if possible, a specialist.