The leaves of poison ivy, oak and sumac mature in the spring and are present all summer and fall. All of these plants have oil or sap called urushiol on their leaves and stems. When this oil touches the skin, many people develop a rash caused by an allergy to these plants.

You can get this rash by direct contact with a plant that contains urushiol. You can also get it by touching something that the oil has stuck to such as pet’s fur, gardening tools or sports equipment. Burning these plants releases particles of the oil into the air. If they land on skin, a rash can occur.

To recognize these plants remember the saying “leaves of three, let them be.” Poison ivy grows as a climbing vine or a low shrub with three pointed leaflets. In the early fall the leaves turn a bright red. Poison oak with its oak-like leaves grows as a shrub. It has three multilobed, hairy leaflets which turn yellow or orange in the fall. Poison sumac grows in swampy areas as a shrub or small tree. It has 7-13 leaflets per leaf.

The rash takes 12-72 hours before you experience itching, redness and swelling followed sometimes by small or large blisters. If you realize you have touched poison ivy wash the affected skin with soap very vigorously within 10 minutes and you may stop the rash. When the rash develops after a plant touches the skin, streaks or lines show where the plant brushed against the skin. While it may seem that the rash is spreading, this is actually a delayed appearance in some areas. The rash does not spread and is not contagious.

Sensitivity to poison ivy tends to decline with age.

One way of preventing poisonous plant reaction is to avoid them and another is to apply an over-the-counter skin barrier product that contains bentoquatum before going outdoors. This may prevent the urushiol from penetrating the skin.

To treat an allergic plant reaction first the skin should be washed with lukewarm water and soap. All clothing should be washed well and anything that may have come in contact with the urushiol should be washed thoroughly. For mild cases cool showers, over-the-counter anti-itch products and Epsom salt soaked cloths will help. Oatmeal baths and baking soda mixtures can also help. For severe reactions see a dermatologist or go to an emergency room.