Don't be rash: Heed 'leaves of three...' advice
TV news was my thing. When I first appeared regularly on D.C. news, I thought I was “da bomb.” It was just a matter of time before someone else dropped a bomb on me. A couple of years later in Charlottesville, Beth Duffy and I were itching to tell NBC29 viewers about poison ivy. I said my neighbors agreed to allow me to tell their story. (I was their matchmaker and they married!)
They are still happily married (never got the seven-year itch), but every time the husband does yard work, his wife gets poison ivy. It turns out that poison ivy toxins cling to his clothes, so the hubby accidentally gives her the rash.
Harmless story? I got an anonymous letter from a viewer saying I broke patient confidentiality (though they weren’t my patients) and probably ruined their marriage by telling this “personal” story. So this viewer said, “Me and the girls will never see you as a doctor since you can’t keep your mouth shut.” (Ah, didn’t my disclosure of my friends’ consent mean anything? And it is, “The girls and I.” Learn some grammar!)
Can people give you a rash?
Toxicodendron is the group of plants that include poison ivy, poison oak, and poison sumac. With exposure to these plants, a contact dermatitis can develop to cause itch, itch, itch!
Up to 40 million Americans seek medical treatment for “poison ivy dermatitis,” in particular farmers, forestry workers, and firefighters.
Urushiol is the bad-boy ester in poison ivy that causes a skin reaction in 50-75 percent of people.
On first exposure to urushiol, a rash takes about 72-96 hours to develop. Once a person is sensitized to urushiol, the rash occurs much sooner, in 12-24 hours, though delayed rashes can occur many days later. Here is some interesting trivia: some folks who are allergic to urushiol can have a cross-reaction to mango rind, cashew nutshell, and ginkgo tree, Indian marking nut tree, and Japanese lacquer tree.
The red rash usually appears in a streaky pattern where the plant’s toxins brushed up against the skin. The reaction can vary from just bumpy to all-out blisters, depending on level of the reaction. The face and– gulp– the genitals can become quite swollen from the urushiol.
The rash lasts one to three weeks but can be complicated by infection from– yes, you guessed it— scratching. So topical and oral steroids as well as antihistamines are often prescribed to stop the itch and reduce the inflammation. Such these plants should never be burned because the smoke can cause a terrible pneumonia.
Most of my patients with poison ivy get it while doing yard work. Dogs can carry in urushiol as well as clothes and hands. Until the urushiol is washed off (and be sure to scrub under the fingernails), it can spread to all body parts. The sooner urushiol is washed off, the better. Fifty percent of urushiol can be eliminated if it’s on skin for ten minutes or less, but 30 minutes on the skin and only 10 percent is removed.
Barrier creams are controversial, although I have some patients who swear by them to prevent urushiol contact.
I was never a Boy Scout, so I’m not that great at identifying all the different types of poison whatevers. In general, the rhyme, “Leaves of three, let them be” (which should be spoken while stirring a cauldron) is a good rule.
So cover up, wash up, and stay away from poison ivy and the gang. The pharmacy has only so many steroids to rash-ion.
Dr. Hook cracks a joke or two, but he's a respected physician with an interesting website, drjohnhong.com. Email him with your questions.