Soothing the sting of poison ivy

By Jay M. Ritt, MD 

Ah, summer. It is the sweetest time of year. But along with the pleasures of outdoor fun come the blistering, itching and redness of the season's most dreaded annoyance: poison ivy.

The raised, red rash associated with exposure to poison ivy (and its cousins, poison oak and poison sumac) is a classic example of an allergic contact dermatitis. The rash is caused by exposure to urushiol, an oily organic substance found in the leaves, stems, roots, and flowers of the plant. The amount of urushiol on the skin, the part of the skin in contact with it, and level of one's sensitivity all contribute to the severity of the resulting rash.

The poison ivy rash is characterized by the appearance of itchy bumps or blisters on the affected areas of the body. These bumps may look like raised, red lines and have been caused by the plant brushing up against the body and depositing urushiol on the skin. The rash may appear in as little as two days or as long as two weeks after exposure and may last from one to several weeks. Interestingly, the rash may appear at different times on different parts of the body, and it may continue to come out even after one's contact with the plant is past.

There are many common myths about the poison ivy rash. One is that you can catch it by touching the affected skin or blisters, or the fluid from the blisters. In fact, the poison ivy rash can only be transmitted by contact with the oil of the poison ivy plant. You can, however, get the poison ivy rash by touching clothing, a pet's fur, gardening tools, sporting equipment, or other materials that have been in contact with the poison ivy plant and oil. 

Another common myth is that the poison ivy plant can be safely destroyed by burning. In fact, it is dangerous to burn poison ivy because it releases urushiol into the air and can cause severe respiratory problems as well as significant facial swelling.

The good news is there are many effective remedies for the poison ivy rash available at your local pharmacy. At South Shore Dermatology Physicians(SSDP), we recommend treating the rash with lukewarm baths with colloidal oatmeal and cool compresses soaked in a solution of water and Domeboro tablets or powder. This helps to relieve the itching, prevent infection and promotes healing. Over-the-counter hydrocortisone cream and calamine lotion can be helpful in relieving the discomfort of relatively mild cases. Antihistamines such as cetirizine or diphenhydramine may also help to reduce itching. It is important to avoid scratching the rash to prevent infection. Likewise, if the rash produces blisters, try to keep the blisters intact to prevent bacteria from entering the open wound.

In some instances, the poison ivy rash requires evaluation and treatment by a Board certified dermatologist. Seek medical attention if any of the following occur:

• The rash is widespread;
• There is severe swelling or blistering;
• There is concern that a secondary infection is developing;
• Over-the-counter remedies are not helping.

Most importantly, if you develop an itchy, blistered, swollen, and reddened area on your skin and you don't know the cause, contact SSDP at 508.535.3376 for help.

Learn how to identify the poison ivy plants and ways to prevent the poison ivy rash on the SSDP blog.

Learn more about the treatment and prevention of poison ivy on the American Academy of Dermatology website.