DermNote

What is Poison Ivy, Oak, or Sumac dermatitis?

Poison Ivy, Poison Oak, and Poison Sumac are related plant species found throughout the United States that can cause an intensely itchy rash when exposed to the skin. The rash, known as an allergic contact dermatitis, arises because the plants contain an oil called urushiol that causes an allergic skin reaction in approximately 50% of people who come in contact with it. These types of rashes are extremely common, affecting tens of millions of Americans each year. People who spend a significant amount of time outdoors in places where these plants grow are at increased risk, and the condition affects people of all ages and ethnic backgrounds. In almost all cases, the rash is limited to the area of skin that was directly exposed to the plant, although handling contaminated clothing, gardening tools, or even pets exposed to urushiol can cause the rash to develop in multiple areas.

Identifying possible exposure to one of these plants can help your physician to diagnose the condition. Poison Ivy and Poison Oak are classically characterized as possessing “leaves of three,” while Poison Sumac leaves possess 7-14 leaflets that give the appearance of a feather.

What are the symptoms of Poison Ivy, Oak, or Sumac dermatitis?

Initially, the areas of skin exposed to the plant will become red, swollen, and intensely itchy. This occurs within four hours to a few days after initially touching the plant for people who have been exposed to urushiol in the past. People who are coming in contact with Poison Ivy, Oak, or Sumac for the first time in their lives may experience delayed symptoms that arise up to three weeks after initial contact. The reddened areas may develop small red bumps and fluid-filled blisters. These bumps and blisters are not contagious, and you should expect the symptoms to self-resolve within three weeks. For some individuals, the affected area of skin may take on a darker color even after the rash disappears. This is often just a temporary part of the healing process, and the skin will generally return to its normal tone within a few months.

How is Poison Ivy, Oak, or Sumac dermatitis treated?

Because contact dermatitis due to urushiol exposure nearly always self-resolves within three weeks, the treatment focuses on reducing the intense itchiness associated with the condition. Your physician may recommend oatmeal baths, cool compresses, calamine lotion, or other strategies to reduce your symptoms. In addition, antihistamines such as Benadryl can be used to reduce itchiness, especially if the symptoms are preventing you from falling asleep.
If you are quickly diagnosed within days of exposure to the plant, your physician may prescribe a steroid cream to rub on the affected skin in hopes of reducing the full extent of your symptoms. Patients who are severely affected by the dermatitis may need to take steroid pills by mouth over the course of two or more weeks in order to sufficiently relieve their symptoms.
Finally, your physician may discuss with you options for preventing future reactions to Poison Ivy and its related plants. Recommendations may include protective clothing, immediate washing of the skin and clothing after suspected contact with a plant, and potentially even the use of a barrier cream on your skin as a preventive measure.

What can I expect from treatment?

All of the treatments described above should help to reduce the amount of itchiness you experience as the rash gradually heals on its own. Certain types of antihistamines, including Benadryl, can make you sleepy. As a result, you should discuss with your doctor which types of antihistamines to take during the day versus at bedtime if you end up requiring the medicine. In the case that you are prescribed oral steroids, be sure to take the full course of the medication exactly as prescribed, as cutting the treatment short can sometimes cause the rash to come back.

When should I be concerned/contact my physician?

You should see your doctor if your rash does not improve within three weeks. Occasionally, the irritated area of skin can become infected by bacteria. If you experience additional symptoms such as a fever, tenderness of the skin, notice pus from the skin, or simply feel that the rash does not seem to be improving even after a few weeks, you should not hesitate to contact your physician. Finally, if you begin to develop rashes in parts of your body that were not exposed to one of the urushiol-containing plants, you should see your physician to investigate further.