Can reactions to poison ivy, poison oak, and poison sumac be prevented?

Only the oil (urushiol) from poison ivy, oak or sumac plants can cause a rash (allergic contact dermatitis). The best way to avoid contact with urushiol and getting a rash is to avoid the plants.

• Learn to recognize these plants, especially those near where you live. The plants may look different depending on the season and the area where they are growing. A county agricultural extension service may be able to help you identify the plants in your area. See a picture of poison ivy, oak and sumac leaves.
• Even though their appearance changes with the seasons, the plants usually contain the same amount of urushiol year-round, even in the winter when they only appear as bare sticks. Black areas on the plants may help you identify them in the winter (urushiol turns black when exposed to air). Living, dormant and dead plants all contain urushiol, although dead leaves do not contain a lot of it.
• You may also try to remove the plants when appropriate. Never handle these plants without vinyl gloves (urushiol can penetrate rubber).
• When you cannot avoid being near poison ivy, heavy clothing (long pants, long sleeves, enclosed footwear) may help prevent the oil from touching your skin. Clothing or any other object that has touched the plant must be handled carefully and washed thoroughly.
• If you are often in areas where poison ivy, oak or sumac grows, you may want to get a product (such as Tecnu or Zanfel) that is designed to remove the plant oil (urushiol) from your skin.
• Barrier creams and lotions can be used to prevent urushiol from contacting the skin or to reduce the severity of a reaction. These creams vary in their potency and are not always effective.

If you suspect that your skin has touched poison ivy, oak or sumac, wash the area to help prevent a reaction. Clothing and other items that may have oil on them should be thoroughly washed right away too.

Poison ivy, poison oak, and poison sumac produce a resin (think of it like an oil) containing reactive, unstable molecules. The unstable molecules as a group are known as "urushiol." They react with our skin, forming complexes to which the body first becomes sensitized, then reacts. The reaction can take some time, so usually the rash appears 6 to 24 hours after contact.

Immediately after contact, washing with soap and cold water (to avoid opening the pores) may reduce the risk of a reaction. However, the best way to prevent a reaction is to not come into contact with the plants in the first place! Therefore, it's very important to know where they are found and what they look like.

Generally, poison ivy is east of the Rockies, poison oak is in the West, and poison sumac is also east of the Rocky Mountains, in very wet areas. Poison ivy does well in disturbed areas and as such is extremely common in suburban and exurban areas.

Poison oak and poison ivy have leaves in groups of three with the middle leaf extending out longer than the others. They also have a reddish tinge to them, from the urushiol making its way to the surface and reacting to oxygen. The stems and vines have an even more concentrated amount of urushiol, so coming into contact with the plants in the winter will likely be worse and harder to avoid (because they can't be recognized by their leaves). Burning them will release the chemicals into the air, which may still cause reactions.

Urushiol is extremely stable, so unless it is washed off clothes (regular laundering with detergent should be fine) or tools (soap and water), it could still easily cause a rash a few years later.