What Percentage of People Are Allergic to Poison Ivy, Sumac, and Oak?

A patient recently asked me what percentage of are allergic to poison ivy. 85% of the American population is allergic to urushiol (Poison Ivy, Sumac, and Oak). Upon first exposure, the skin reaction doesn’t happen for 14 days; subsequent exposures produce reactions in 2 days. The rash lasts an average of three weeks. Here are some tips on dealing with this common summertime rash:

  1. Urushiol  is spread very easily, such on clothing, so be sure to clean thoroughly after being in an area with a high concentration of one or more of these plants.
  2. If you develop a rash, try not to scratch it. Take cool showers or baths to reduce swelling and itchiness. Some topical products you can apply to the affected area are calamine lotion and hydrocortisone cream; both can be purchased over the counter.
  3. The best way you can prevent an allergic contact dermatitis reaction is to wear long pants and sleeves when you are in areas that poison ivy is growing.
  4. If you do manage to come into contact with the plant, make sure that you wash all exposed skin with soap and water as soon as you possibly can. If you rinse off exposed skin within five minutes of coming into contact with urushiol, you can completely remove it.


Poison Plant Identification. , Pictures of Poison Oak & Ivy | Tec Labs. http://www.teclabsinc.com/tips-info/images-video/images/poison-plant-identification/. Accessed June 24, 2016.

Did you know? Poison Ivy, Sumac and Oak  |  American Skin Association. http://www.americanskin.org/resource/poisonivy.php. Accessed June 24, 2016.