Summer is a great time for hiking (provided you incorporate appropriate sun protection measures!) In addition to getting exercise and being in the midst of beautiful scenery, exposure to poison oak is common. Most adults will develop an allergic rash upon exposure to urushiol oil, a resin present in poison oak, ivy, and sumac. The intensity of the rash varies and tends to be more severe with subsequent exposures. The eruption usually develops within days of exposure and commonly spreads beyond the sites of contact due to the body’s immune response to the resin. The rash usually appears as red, swollen, linear streaks that have a “painted on” appearance. Fluid filled blisters are common but the contents are not contagious.
Avoiding exposure to the plant is achieved by wearing long pants, long sleeved shirts, and following the advise, “leaves of three, let them be!” If you think you’ve been exposed, removing the resin by washing with soap and water might prevent the rash from developing. Laundering clothing separately in warm water is also a good idea.
Finally, if you develop the rash, OTC hydrocortisone cream and oral antihistamines such as diphenhydramine (Benedryl) or cetirizine (Zyrtec) can help mild reactions. For moderate to severe reactions, prescription topical steroids or oral steroids (eg prednisone) are often required.