When you have a case of poison oak or ivy, you know what you want to do: put your salad fork to better use and... scratch.

Sympathizing dermatologist Stephen B. Tucker of The University of Texas Medical School at Houston says, “I always tell my patients that if they itch, they will want to scratch. To tell a patient not to scratch is impossible. My job is to get rid of it. If they are still itching, then I haven’t done my job. Meanwhile, scratching will do no serious damage.”

Summer fun spoilers, like poison oak, ivy and sumac, and a host of other rash-causing plants can wreak havoc with the skin on some people, and cause nary a problem on others. “But scratching does not spread it, and it is not contagious.”

Then, why does it spread to every place you touch?

It only seems that way. The reason you might think you’ve spread it all over yourself from scratching is that when you are exposed to poison oak or ivy, you have places on your skin with higher and lesser concentrations of the oily exudate called urushiol—that stuff that puts the “poison” in oak and ivy. “You initially break out where there’s the highest exposure. Then your immune system kicks into high gear, and over the next two weeks it finds other places you have exposure, making it seem like you are spreading it with contact.”

Tucker says though, that since urushiol is an oil, once you’ve washed it off with soap and water you can’t spread it. “But where it has already bonded to a protein in your skin, there is some possible residual oil.” Washing immediately might save you from a more severe or prolonged reaction.

A sticky situation

Urushiol, found in the sap of poison ivy, oak, and sumac, is hardy stuff that clings to unwashed clothes, camping gear, bicycles – just about anything you use outdoors. Rain won’t necessarily wash it off and sun may not dry it out – urushiol remains potent for months. Even if you avoided the brushy areas that contain the offender; even if you let those “leaflets three” be, your outdoor gear might have spread the “poison” to you.

Urushiol gets on your skin by direct contact with the plant, or something that has come into direct contact with the offensive plant. The first time you get urushiol on you—if you are one of the unlucky two-thirds of the population who will react to it—you might not know it. It might take five to six days to become “sensitized” to it, that is, to itch and have rash. By the time you feel that initial reaction, your hiking vacation or gardening day may be long forgotten. “People come in to my office with no idea they’re reacting to poison oak or ivy.”

But the next time, it will only take eight to 48 hours to react. By then you’ve washed off most of the oily toxin, but what skin had already had contact will itch and rash.

Treatment

“Your comfort level will dictate your treatment,” Tucker says. If you know you have inadvertently brushed against poison oak or ivy, find a shower if possible. Products such as Zanfel, are advertised as able to wash away the urushiol.

Tucker points out that if you can react quickly enough, you can wash off the oil with soap and water. “But unless you can wash it off within just a few minutes,” he warns, removing the urushiol won’t completely stop it. By then your immune system has already recognized the oil (and its bonding activity with protein components in your skin) as a foreign substance and has sent antibodies to fight its effects, hence the coming misery.

When the red welts and leathery-looking bumps appear, popular over-the-counter creams, lotions and sprays can fight the itch, help dry the rash, and soothe your ravaged skin. Common creams contain aloe, Burrows solution (aluminum acetate), calamine, camphor, hydrocortisone, menthol, manganese sulfate solution, oatmeal, pramoxine hydrochloride, zinc oxide or any combination of those ingredients.

Some people use topical Benadryl or oral antihistamines. Others take cold baths, use ice packs, or apply a paste of water and baking soda. Tucker says some patients mix urban legend with home remedy by applying toothpaste or even Preparation H. “But know that over-the-counter medications may contain ingredients that you might react to, as well. So be alert for adverse reactions and wear loose, cool clothes that cover the lesions,” He advises. Though difficult in the South, avoid hot, sweaty, sticky situations until you heal.

When to call the doctor

“You call the doctor when the itching is so severe that it interferes with your life,” Tucker says. “Itching can be as bad as severe pain, and can cause just as much suffering.” Treatment usually involves steroids for their anti-inflammatory action, by injection or pills.

Tucker says that often general physicians will prescribe a very short course of oral steroids. “Occasionally the dosing cycle is too short—just long enough to relieve the initial symptoms but not long enough to suppress the reaction for good. If there’s a relapse, it is much harder to treat the second time around.” Tucker recommends a longer course, based on how long the rash has been present.

Beware of burning leaves

This autumn, during leaf-burning time, contact your doctor immediately if you have inhaled urushiol from burning plants or leaves. Even plants that were mowed or cut last year will release toxins if burned. The reaction can be profound with widespread lesions, facial swelling, burning throat or itching eyes. “The oil goes ‘up in smoke’ so to speak, into vapor form. Patients have no clue what hit them.”

The ultimate treatment is a combination of soothing creams and steroid pills.

Prevention

The best way to avoid contact is to wear protective clothing when out in the wild, even if the “wild” is just your overgrown backyard garden. “And where the gaps are, like the wrists, ankles, face, use IvyBlock, available at any drugstore,” Tucker says.

UPDATED: 8-08-2007

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