Don't Touch that Plant!
by Roberta Lee, MD (topic expert: health)

Tis the time of year to be out of doors, but it is also the time we are likely to get a contact dermatitis rash from poison ivy, oak, or sumac. Contact dermatitis is the medical name for an inflammation of the skin or rash that results from direct contact with certain substances. The rash is red and sometimes results in blistering. It is usually itchy but is not contagious or life-threatening, yet it can be very uncomfortable. The cause can be soap, cosmetics, jewelry, or weeds, including poison ivy or poison oak.

Poison ivy, oak, and sumac plants are the single most common cause of allergic skin reactions in the United States. They are caused by contact with urushiol which is found in the sap of the plants. Between 10 and 50 million Americans develop an allergic reaction to poison ivy, oak, and sumac yearly, and 95% of people exposed to urushiol will have an allergic reaction at some point in their life.

Urushiol is a colorless or pale yellow oil that oozes from any cut or crushed part of the plant, including the roots, stems and leaves. The oil is active year round -- I found that out in my second year of medical school. As an avid hiker, even in the winter, I unknowingly hiked through a tangle of poison ivy and had the worst rash I have ever had in my life simply because I could not identify the offending plant without its leaves.

Poison ivy, oak, and sumac severely impact outdoor occupations such as firefighters, surveyors, park and highway maintenance workers, utility workers, and farmers, according to the National Safety Council. Poison oak is responsible for more than 50% of worker?s compensation cases in California alone.

Contact with urushiol can occur in three ways: direct, indirect, and through airborne particles. Direct contact is touching the sap of the toxic plant. Indirect contact involves touching something which has urushiol on it, such as the animal fur, clothes, boots, garden tools, sporting or camping gear or any items that have come in contact with the plant (including your hands).

The first contact, which can occur without a person knowing, potentially creates hypersensitivity to the allergen without causing a rash. Interestingly, prior contact without rash eruption does not guarantee immunity upon subsequent exposures.

Once urushiol touches the skin, it begins to penetrate in as little as 10 minutes. In those who are sensitive, a reaction appears usually within 12 to 48 hours. It takes roughly two weeks to heal and any part of the body can be affected, especially where skin is thin, such as the face.

Exposure to burning poison ivy is dangerous two ways: it can cause a skin rash and severe internal inflammation from inhaling the oil.

Poison ivy, oak, and sumac grow almost everywhere in the United States, except Hawaii, Alaska and desert areas. The general distribution of these plants are:

• Poison ivy: east of the Rocky Mountains and in Canada.
• Poison oak: Western and Southeastern United States, Canada and Mexico.
• Poison sumac: eastern states and Southern Canada.

Prevention is the best strategy, but difficult if you are regularly in an area where any of these plants are grown since the oil can spread from indirect contact.

Here are the recommendations on prevention and treatment from the Food and Drug administration website:

Tips for Prevention

• Learn what poison ivy, oak, and sumac plants look like so you can avoid them
• Wash your garden tools and gloves regularly. If you think you may be working around poison ivy, wear long sleeves, long pants tucked into boots, and gloves.
• Wash your pet if it may have brushed up against poison ivy, oak, or sumac. Use pet shampoo and water while wearing rubber gloves, such as dish washing gloves. Most pets are not sensitive to poison ivy, but the oil can stick to their fur and cause a reaction in someone who pets them.
• Wash your skin in cool water as soon as possible if you come in contact with a poisonous plant. The sooner you cleanse the skin, the greater the chance that you can remove the plant oil or help prevent further spread.
• Use the topical product "Ivy Block" if you know you will come into contact with the poisonous plants. This the only FDA-approved product that is available over the counter (OTC). Information on this product can be found at www.ivyblock.com.

Tips for Treatment

Don't scratch the blisters. Bacteria from under your fingernails can get into the blisters and cause an infection. The rash, blisters, and itch normally disappear in several weeks without any treatment. Here's how to relieve the itch:

• Use wet compresses or soaking in cool water
• Apply OTC topical corticosteroid preparations or take prescription oral corticosteroids
• Apply topical OTC skin protectants, such as calamine, labeled to dry oozing and weeping or to relieve itching and irritation caused by poison ivy, poison oak, and poison sumac

Plan identification (including photos) and more medical information sources online:

1. American Academy of Dermatology: www.aad.org/public/publications/pamphlets/skin_poison.html
2. Medline/NIH site: www.nlm.nih.gov/medlineplus/poisonivyoakandsumac.html
3. Food and Drug Administration site: www.fda.gov/ForConsumers/ConsumerUpdates/ucm049342.htm