How does poison ivy, oak and sumac work?

Not sure what caused your poison ivy/oak rash? Many people know what a poison ivy. oak or sumac rash looks and feels like, but do not really understand why the plants cause such a painful, itchy rash. Once you understand how the  plants work, it is easier to avoid a rash.

Poison ivy, oak and sumac all produce the same rash-causing, resinous oil called urushiol (pronounced ooh-roo-she-all). It is found in all parts of the plants including the leaves, stems and roots. It can stay potent for many years, even on dead plants. The oil can be transferred easily to skin, clothing, and other objects and then can be transferred on again. For some people, it can take a very small amount to cause a very big reaction.Rhus Dermatitis

85% of the population is allergic the urushiol found in poison ivy, oak and sumac plants. It is your body's immune response to this allergen that causes the painful rash. Depending on your sensitivity to urushiol, your body's reaction can vary from mild to severe. Poison ivy, oak and sumac rash symptoms can include:

  • Itchy skin where you came in contact with the oil
  • Redness or red streaks
  • Hives or small bumps in the skin
  • Fluid filled blisters that may leak. Note that the fluid in the blisters does not cause the rash to spread, contrary to common myths about poison ivy and oak.

Symptoms of poison ivy, oak or sumac rash usually start within a day of coming in contact with urushiol, but can take as long as two weeks to show up. Using an OTC treatment for poison ivy can help alleviate the symptoms for most people. For more severe reactions, it is best to consult a doctor.

In addition to coming in direct contact with the plant, you can also get poison ivy, oak or sumac through secondary contamination. Urushiol can stay on objects such as tools, clothing, gloves, and shoes for several years. Your pets can also transfer the oil to you if they run through the plants and get it on their fur. The best way to prevent secondary contamination is to remove the oil from any possible secondary sources.

See our article, Unexpected Sources of Poison Ivy or Oak Rash.