What Is Poison Oak?
Poison oak, also called western poison oak or Pacific poison oak, is one of the causes of allergic contagious dermatitis (ACD). Poison oak may appear as a dense shrub in open sunlight or as a woody vine under shadows. Similar to poison ivy, poison oak has three smaller leaflets on each leaf. Poison oak plants contain an oil called urushiol, a toxic chemical in their leaves, stems, and roots. Many people develop an allergic reaction through direct or indirect contact with urushiol or inhalation of urushiol smoke. The initial immune reaction begins once the poisonous substance is absorbed onto their skin or through mucous membranes like the nose or lips. Together with poison ivy, poison oak leads to 10% of lost work time in the U.S. Forest Service. Hundreds of firefighters in California's coastal ranges are so severely affected that they cannot work.
What are the symptoms of poison oak?
Poison oak oil can cause serious allergic reactions in the majority of people. Typically, poison oak takes 12-72 hours to penetrate the skin. Once absorbed by the skin, poison oak can induce severe itching, redness, and swelling, followed by small or large blisters on the skin. The onset rash may appear on any part of the body after a short incubation period. However, the rash itself generally does not spread, and it is not contagious between individuals.
The sensitivity to poison oak tends to develop with repeat exposure and varies between individuals. Generally, sensitivity to poison oak tends to decline and sometimes disappear as people age. Children who have reacted often experience a decrease in their sensitivity by young adulthood. Nonetheless, essentially anyone who has developed a prior sensitivity through exposure to poison oak may develop an allergic reaction.
How Long Does Poison Oak Last?
Poison oak's resin, called urushiol, can remain active for a very long time. When an allergic reaction occurs after contacting poison oak, the first thing to do is to wash the skin thoroughly with warm soap and water and launder any clothes that may be contaminated with poison oak. This should include towels used to clean the skin. Some soothing remedies such as showering with cool water, applying over-the-counter anti-itching cream, oatmeal baths, or baking-soda mixture may help lessen the discomfort in mild cases. If the allergic reaction is severe, one should contact a physician or go to the emergency room, and some prescription medications including topical and oral steroids may be needed to reduce the swelling and itch.
What Should I Do to Avoid Poison Oak?
- Learn to recognize and avoid contacting poison oak.
- Wear long pants, long sleeves, boots, and gloves to protect the skin.
- Apply an over-the-counter skin barrier product that contains bentoquatam (IvyBlock) to prevent poison oak from penetrating the skin.
- Remove plants if they grow near your home.
- Wash immediately after a suspected exposure.
- Avoid rubbing when the allergic reaction develops because it may lead to secondary bacterial skin infection.
- Try not to touch objects that may be contaminated with poison oak.
- Never burn poison oak to get rid of it.
- Never touch poison oak plants, even if they dead, because they may still contain urushiol (it can remain active for up to five years).
Skin Problems and Treatments Resources
Fitzpatrick's Dermatology in General Medicine