Poison Ivy & Oak

(Rhus Allergy)

What causes the Poison Ivy rash?

Poison Ivy and Poison Oak rashes are caused by an allergy to the juices of these plants – called Rhus plants. You don’t have to come in direct contact with the leaves, roots, or branches of Rhus plants to get the rash. The plant juice can reach your skin indirectly when you touch clothing or a pet that carries the plant juice.

Like other allergies, Rhus allergy is acquired; you’re not born with it. While some lucky people never become allergic to Rhus plants, most persons become sensitized at some point and remain allergic. Unfortunately, it is difficult to desensitize persons allergic to Rhus plants. This is typically performed through an allergist.

Is Poison Ivy contagious?

Your Poison Ivy rash is not contagious. The fluid in the blisters does not spread the rash. Rhus rash doesn’t appear immediately after exposure to the plant juice, but only after a time called the latent period. This latent period between exposure to the plant and appearance of the rash may be as short as 4 hours or as long as 10 days, depending on individual sensitivity and the amount of plant contact. Sometimes more rashes appear after treatment has begun. These new patches are areas that had a longer latent period.

How are Rhus rashes treated?

Rhus rashes are self-limited – sooner or later they clear up without treatment. Letting nature take its course is reasonable with mild Rhus rash. Severe Poison Ivy and Poison Oak rashes are treated by are doctor for patients in our region to ease the misery and disability they cause. Systemic cortisone is dramatically effective in treating Rhus rash. If you have a peptic ulcer, high blood pressure, or diabetes, you should take cortisone only under close medical supervision.

Systemic cortisone is needed during the early, severe stages of Rhus rash, since remedies applied to your skin won’t penetrate deeply enough. Compress crusted or oozing areas for 15 minutes twice daily with a mixture of 2 – 4 tablespoons white vinegar in 2 quarts of cool water. Ice packs or cold showers or baths will temporarily relieve your itching. Some persons find they get more relief by putting very hot water on the itchy areas. After 12 – 24 hours, cortisone will take over and control your rash and itch.

Improvement in your rash should be prompt and steady. It depends on getting enough cortisone. If you don’t improve steadily, please telephone our physician so we can modify your treatment.

When the swelling has gone down, cortisone cream or ointment will help your rash heal. Don’t put anything on your rash except the prescription cream, water, and the vinegar-water mixture. You may bathe or shower as usual; keep the water as cool as you can stand and don’t use soap on your rash, as it irritates.

Can Rhus rash be prevented?

The only way to prevent Rhus rash is to avoid contact with the plant juice. It’s traditional advice to wash with strong soap after poison ivy or poison oak exposure. This does no harm, but in order to prevent a rash, you have to wash within 15 – 30 minutes of exposure. If you can do so, simply washing with water and mild soap will effectively remove any plant juice from clothing, pets, or tools. Strong soaps are unnecessary. Rhus plants may cause rashes throughout the year. Roots and stems can cause a rash just as much as the leaves. If you don’t recognize Poison Ivy or Poison Oak plants, have friends or neighbors point them out so you can avoid them.

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