Dr. Alan Greene on Treating Poison Oak, Ivy, or Sumac

Treatments for common and severe poison plant rashes.

Question

How do you treat poison ivy, poison oak, or poison sumac?

Answer

Poison ivy, poison oak, and poison sumac together produce more cases of allergic contact dermatitis than all other allergens combined. The resulting rash can range from mildly unpleasant to a true emergency with intense swelling, blistering, and oozing. With even a moderate case, as you may have experienced, the itching can seem unbearable.

Treatment

Most of the treatments are aimed at reducing the itching until the self-limited rash runs its course, which takes about two weeks. Since easing the itching is the important result, trial and error works very well. If one of these suggestions seems to work, by all means, stick with it.

Most people find that cool compresses in one form or another are quite soothing. Try using a towel or washcloth soaked in either plain tap water or Burow's Solution (an astringent solution -- you can make it yourself using Domeboro tablets or powder packets available over the counter). This can help relieve the intense itching and remove dry crust that has formed as a result of the rash.

A fan blowing over the cool compress will diminish some of the heat of the itching and help to dry up some of the ooze coming from the rash. As the skin is cooling, the blood vessels compress and that cuts down on the itching and the new ooze. This is especially good during the two or three worst days of the rash.

Along the same lines, some dermatologists recommend rubbing an ice cube gently over the rash several times a day, then letting the skin air dry. Soaking in a tub, particularly using an oatmeal bath such as Aveeno, can also be very soothing to the itch. Be sure the bath is cool or lukewarm, but not hot, as heat tends to make the rash even more inflamed.

After cooling the rash (using any of the forms mentioned above), coat it with a lotion such as calamine. This continues to relieve the itching and helps to dry up the blisters. Be sure to check the expiration date on an old calamine bottle in your medicine cabinet, since it may not be effective after the expiration date. Be sure the lotion does not contain benzocaine, zirconium, or a topical antihistamine, such as Benadryl. These can actually make the rash worse by producing their own allergic reactions when applied to already sensitive skin.

Smearing on hydrocortisone or other topical corticosteroids will help suppress the itching and give temporary relief, but it does little to hasten the drying up of the rash. Similarly, taking an oral antihistamine, such as Benadryl, can help with the itching quite a bit, but it doesn't speed up resolution of the rash. Taking Benadryl at nighttime will make most people drowsy and help them sleep through the night without itching. Again, don't use Benadryl cream or spray topically, because this can cause its own reaction.

Severe Cases

In severe cases of poison ivy, poison oak, or poison sumac, it's a good idea to see a doctor. Sometimes large blisters need to be drained, and sometimes an oral steroid such as prednisone may be useful. Systemic steroids produce rapid resolution of both the itching and the rash. If they are needed, a gradually tapering dosage over about 12 days should be given. The dosage needs to be tapered to avoid side effects after discontinuing use, and the entire course should be taken since stopping earlier may result in a rebound rash as bad as the original.

Prevention

Allergy shots are available to help prevent recurrences of the poison ivy, poison oak, or poison sumac rash. Unfortunately, the shots for this are frequently ineffective and should be reserved only for those who are extremely sensitive. Prescription pills containing small amounts of extract from the plants have been used for immunization. However, these pills can cause uncomfortable side effects. The pills are recommended only if given before contact with the plant and only for individuals who come into frequent contact with the plant. Using topical creams (such as Ivy Shield, IvyBlock, Hollister Moisture Barrier, Stokogard Outdoor Cream, or Hydrophil) can also help protect against contracting the rash.

 

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.

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