Poison Oak and Ivy—Very Touchy Subjects
POISON oak is not an oak, nor is poison ivy an ivy. The names come from the resemblance of their cluster of three leaves to some forms of oak leaf, and from the plant’s habit of climbing like an ivy. Several species come under these common names, and all are of the genus Rhus. The general practice is to call the bushy types poison oak and the climbing ones poison ivy.
The North American continent is the only continent that plays host to these plants, one variety or another being found in almost every kind of environment, from swamps to dry, hilly terrain. They can be beautiful. The young leaves are a deep-wine color, then they become a glistening green, and finally turn crimson in the fall. Admire them if you will, but keep your distance!
Their sap contains a chemical called urushiol, and a very minute quantity on your skin can give you a painful case of poison ivy dermatitis. The slightest brush against a leaf can cause an itching rash. Blisters develop from which a clear liquid oozes, and severe cases cause swelling and even fever. It takes several hours after contact for the symptoms to appear, and sometimes a few days. The toxin is not superficial, but penetrates the surface of the skin to infect the tissue underneath. That is why it takes time to develop.
It is so easy to contract a case of poison oak that for years it was thought that the plant gave off a miasma or vaporous exhalation that infected persons who never touched it. That is not true, but a person doesn’t have to touch the plant with his bare skin to be affected by it. If a person’s clothes brush against the plant, he can get it by touching his clothes months later. Petting a dog that has run through a patch of poison oak is sufficient to get a bad case of it. Smoke from the burning plant can carry the toxic urushiol.
To illustrate the persistence of this poison, a pair of white canvas gloves used to collect poison ivy lay in a closet for ten months, and was then washed in hot water and strong laundry soap for ten minutes. A volunteer then handled the gloves, and the next day he had poison ivy dermatitis! This shows why a usual precaution recommended—washing with yellow laundry soap after a trip in the woods—oftentimes does not work. It is still good advice. It may help, and it can’t hurt. Some authorities advocate it if it can be done within thirty minutes after contact, saying that there is a chance that it may inactivate the poison.
Once the rash has started, there are no really effective treatments. It usually has to run its course, taking from two to three weeks to do this. Calamine lotion will soothe the itching. Refraining from scratching will prevent aggravating it and perhaps spreading it. In severe cases a physician may be able to prescribe a treatment that will relieve the suffering. There are several cortisone-like medicines that are used. But once the poison is contracted, it is basically a waiting game for relief to come.
With poison oak the old saying is true: an ounce of prevention is worth a pound of cure. Various creams and ointments are sold to keep the urushiol sap off the skin. They do little good. Some doctors give doses of urushiol, orally or by shots, to build up immunity, but this has not proved very effective. A better protection is clothing that prevents the plant’s contact with bare skin. The best preventive is recognizing the plant and keeping your distance. Don’t touch it, or anything it has touched.