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  • To your Health

    A crash course on poison oak rash

     By Dr. Roger Hicks 


    With spring comes a “rash” of people who will suffer from the itchy skin problem caused by poison oak. “Leaves of three, leave it be” is a familiar rhyme to many of us who grew up loving the outdoors. It’s a helpful way to identify poison oak and poison ivy, but it’s far from foolproof because you can get the rash any time of year, including the winter.


    There is rampant urban mythology about poison oak. One of the biggest myths is that you must touch the leaves to get it. In fact, the rash is an allergic reaction to urushiol, an oil in the plant that is present not only in the leaves, but also the stems, roots and berries. The oil will stay on anything it touches, including under your fingernails as well as your pets, tools, gloves, clothing, shoes and bedding, and can be transferred to other parts of your body or someone else until washed off those sources. As a result, re-exposure is common as people unknowingly wear clothing or play with pets that may have the oil on them. 


    Another myth is that you need to wash with a special soap, like Tecnu or Fels Naptha. You don’t – any detergent soap is effective. The important thing is to wash as soon as possible after exposure. If the oil is on you more than 20-30 minutes and you are one of the 3 out of 4 people who are allergic, you’ll get the rash. But wash anyway, making sure to clean your fingernails and avoid vigorous scrubbing, which can be counterproductive. Washing after the rash has appeared is helpful only if you haven’t bathed since your exposure, because it just removes any remaining oil. 


    The rash can cause blisters, and many people think the blister fluid can spread the rash. It doesn’t. Keep in mind the rash is an allergic reaction to the oil, not an infection. The fluid in the blisters doesn’t contain any oil so can’t spread the rash. 


    When the rash appears depends on three things: how much oil you got on you, the type of skin (the thinner the skin, the more quickly it appears; people almost never get it on their palms or soles of their feet), and how sensitive you are. It appears as quickly as four hours after exposure on some, while for others it can take four days. New blisters can continue to appear for 21 days in first-timers. It affects people of all ages, ethnicities, and skin types, although sensitivity does seem to wane with age.

    Untreated poison oak usually resolves on its own in 3 weeks. Secondary infection is the most common complication and can happen where there is raw skin from scratching or broken blisters. Healing is delayed by infection.


    The best way to prevent poison oak is to avoid contact with it by learning to recognize it throughout the year, including in the winter when it has no leaves. If you know you are going to be exposed to poison oak, wear long sleeve clothing and gloves. Urushoil oil can seep through thin clothing and penetrate rubber or latex gloves, but not heavy-duty vinyl or leather gloves. Putting on a good barrier cream beforehand helps some; those with 5% bentoquatam, like IvyBlock are most effective. The idea is the barrier cream prevents the oil from contacting your skin, and you wash it off as soon as possible after exposure. Keep in mind the oil is still potent when the plant is dead and dried out, is stable at high temperatures and dispersed in smoke, so you can get it from burning it. 


    Urgent care facilities such as Yubadocs see poison oak year-round and can provide accurate information and useful treatments that are far more effective than anything you buy over the counter. Most people will see the rash go away in a few weeks, but if you show signs of infection or have swelling around your eyes, face or genitals, you should see a doctor right away.


    Enjoy the warm weather and stay aware of the leaves of three that can leave you scratching your way into summer!


    A director of the Urgent Care Association of America from 2011 to 2017, Dr. Roger Hicks served as the Association’s treasurer and then secretary. He is a founder and current board member of the Urgent Care Assurance Company, a malpractice company specializing in urgent care. He is the founding President of the California Urgent Care Association. He is also the founding president of the South Yuba River Citizens League and served on SYRCL’s Board of Directors for 30 years