avoiding rash from poison ivy

Protecting yourself from poison oak, poison ivy and poison sumac

Poison ivy, poison oak and poison sumac all share a single, miserable compound that makes them so notorious -- urushiol oil. When absorbed by the skin, just a miniscule amount of this sticky sap can create an itching and oozing rash in 80%-90% of us. How toxic is it? Just enough urushiol oil to cover the head of a pin would cause an allergic reaction in 500 people. 1/4 of an ounce is enough to effect everyone on earth!

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To some of us who are highly reactive, it seems like just getting near these plants can make us break out. The fact is that the urushiol oil is locked in the leaves, stems, roots and berries so the plant must be bruised in order for the toxic oil to be released. The bad news is that they bruise, break or tear easily, especially in spring and early summer when the leaves are most tender. In addition to brushing up against the poisonous plants directly, there are many ways we be exposed to urushiol oil indirectly:

Think you're one of the lucky ones who are immune? Don't push your luck. We all react differently when exposed to urushiol oil. Some of us who showed little response as children will develop an allergy to it as adults. Others may have less of a reaction as we age. For the majority of us, however, our allergic response becomes more vigorous with repeated exposure. And the more of it we come in contact, the worse we break out. (The average exposure gets 100x more urushiol on our skin than is needed for a rash to break out.)

Are even American Indians allergic to urushiol oil?

Yes. In the past, Native Americans were probably just expert at recognizing and avoiding poison ivy, oak and sumac.

Are animals allergic to urushiol oil?

Animals rarely have an allergic reaction to poison ivy, oak or sumac. The berries of the plants are an important food source for birds and the leaves are a favorite with deer, mice and insects. Since household cats and dogs, seldom have an allergic response, second hand exposure (from pets to humans) of urushiol oil is very common. If there is a chance that your pet has been exposed, put on dishwashing gloves and shampoo him or her before petting or handling.

Is there any way to develop immunity to poison oak, poison ivy or poison sumac?

Probably not. Though some people feel they've developed urushiol oil immunity through a variety of unconventional ways, like eating tiny amounts of the leaves early each spring or drinking milk from goats that graze on these poisonous plants, medical experts seem to agree that there is no safe, reliable way to desensitize ourselves.

How to protect yourself if you're hiking or working in the yard and may be exposed:

  • recognize what poison ivy, oak and sumac look like. (The saying, leaves of three, let it be is a good, is a general rule regarding poison oak and ivy but for a quick description see Outsmarting Poison Ivy and Other Plants. The most detailed description we've found is in the free 12-page booklet, Positively Identify Poison Ivy and Poison Oak. Poison sumac has 7-13 leaves and looks nothing like poison ivy or oak.
  • stay on trails to minimize your risk of exposure.
  • wear long sleeve shirt, pants (tucked into boots or socks) and, if appropriate, gloves.
  • if you know that you will likely be exposed to urushiol oil, apply blocking cream (such as Ivy Block) to exposed area, 30 minutes beforehand, just like you would apply sunscreen lotion.
  • afterwards, wash clothes and shoes in hot water and soap. If shoes cannot be washed, they should be wiped clean with rubbing alcohol.
  • shampoo pets if they may have been exposed.
  • wipe tools clean with rubbing alcohol or wash with soapy water.
  • we found this tip at the Ohio State University Agriculture Safety Program web site and the Poison Ivy Information Center but the national park service says not to do it: As soon as possible after you have been exposed, wipe areas of the body that may have been exposed with rubbing alcohol and then wash the exposed area. Do not go out and possibly re expose yourself after following this step, since rubbing alcohol removes natural oils in your skin, thus decreasing your natural defenses.
  • shower in cool water with a degreasing soap (we use dawn dish detergent), as soon as possible. (Warm water can draw the urushiol oil deeper into your skin. avoid taking a bath until you feel the oil has been removed from your body -- showers will minimize the chance of the oil spreading.

How long before possible rash will appear after exposure? How long before it has run its course?

As soon as a few hours or as long as two days. If someone is highly sensitive, however, or they've been exposed to a lot of the oil, medical treatment may be needed. Swelling could be so severe that one's breathing could stop.

It is possible for some body parts to respond later than others because:

  • thin-skin areas are more sensitive than areas with hair or where skin is thicker.
  • they may have been exposed to differing amounts of urushiol.
  • exposure may be spread out over time by touching pets, sports equipment, tools, etc. that are carrying the oil.

What you can do if the telltale, red, bumpy rash of poison ivy, oak or sumac appears:

  • Wait it out. In most cases, the rash and oozing will be over in 1-3 weeks with the most discomfort occurring from days 4-7.
  • Manage the discomfort with over-the-counter hydrocortisone cream, calamine lotion, oral antihistamine like Benadryl or Zyrtec or washing with a post-exposure soap like Zanfel that can draw absorbed urushiol oil from the skin.
  • See a doctor if you a fever develops or areas around the eyes or mouth are affected.

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Join the conversations:
Showing comment(s)
March 23, 2013
Something I hadn't realized until talking to the pharmacist recently about itch-relief from poison ivy is that calamine lotion loses its potency over time. I used to always apply whatever old bottle of calamin lotion I could dig up and it never really anything. I can't believe how much relief it's providing now that I have a fresh bottle (although what I purchased also contains an analgesic called Pramoxine HCI. CVS didn't carry any pure Calamine.)
August 23, 2013
Do you know if a person can get shots from the allergist to reduce their reaction to poison ivy? And once, a person has a breakout, I wonder if misting the area with clove oil would dull the itching or if that would burn the skin? Nothing I've tried helps and I'm afraid of overdoing it on the Benedryl. Thanks
June 17, 2015
As if things weren't already bad enough for us outdoor lovers who are highly allergic to poison ivy, I see that things may get even worse. Apparently, poison ivy, responds most favorably (among the plants tested) from climate change. As carbon dioxide levels continue to rise, poison ivy explodes both in terms of overall growth rate and urushiol oil production: http://www.pbs.org/newshour/rundown/is-poison-ivy-getting-worse
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