Illustration

What is poison ivy, sumac, or oak?

"Poisoning" from plants such as poison ivy, sumac, and oak is an allergic reaction that results when the skin touches these plants and their oils. Most people develop a rash, blisters, and itching after contact with them. Cases usually occur in the spring and summer.

Poison ivy and oak have three leaves on each stem and grow as a vine or bush. Sumac has two rows of leaves opposite each other and one leaf at the end of the stem. It grows as a bush or tree. The leaves of all three plants are shiny and coated with an oily chemical, which causes the allergic reaction. The oils are also in the stems and roots of these plants.

How does it occur?

The reaction occurs after touching poison ivy, sumac, or oak. A reaction can also occur after contact with anything else that may carry the plant's oils, including ashes and smoke from burning plants. It can also be spread by touching oil left on clothes or tools. The rash often appears on the face first and then on other exposed areas of the body. Typically it is first noticed 24 to 48 hours after contact. How bad the rash will be depends on the thickness of your skin and how much contact you had with the plant's oils.

Sometimes there is a delayed reaction, and the rash develops on one area of your skin after the others. The rash cannot be spread by scratching itchy skin or from oozing blisters. However, scratching may lead to infection of the open sores.

What are the symptoms?

The symptoms of an allergic reaction to poison ivy, sumac, or oak include the following, from least serious to most serious:

• itching, often intense
• red blotches that can be either raised or flat
• blisters, which may show up in lines
• fever
• headache
• swelling of your throat and eyes
• overall swelling of your body
• general feeling of discomfort
• stomach cramps, nausea, vomiting, diarrhea.

How is it diagnosed?

Diagnosis is based on your having the symptoms listed above and on a physical exam by your doctor.

How is it treated?

To treat poison ivy, sumac, or oak, follow these steps:

• Remove your clothes and shoes and wash them in detergent and hot water.
• As soon as possible, wash all exposed skin with strong soap and water (or just water) to remove the plant's oils.
• Apply cloths soaked in aluminum acetate solution (Burow's solution), then calamine lotion or ointment to reduce the redness, ease the itching, and help dry up the blisters. Or take lukewarm baths with cornstarch (1/2 cup) or colloidal oatmeal added to ease the itching. DO NOT use topical antihistamines.
• Cover any oozing blisters with a clean gauze bandage soaked in a baking soda and water solution.

If the rash spreads to your face, mouth, eyes, or genitals, or if you develop a fever, headache, extreme redness, pus, or other severe symptoms, see your doctor. He or she will recommend one or more of the following:

• applying corticosteroid ointment or cream to the affected areas two to three times a day, gradually reducing to once a day
• taking oral corticosteroids such as prednisone
• taking oral antibiotics or using an antibiotic cream if an infection develops.

Because these are all potent drugs, ask your doctor about any possible side effects or interactions with other drugs you may be taking.

How long will the effects last?

In most people, the condition clears up in 2 to 3 weeks.

How can I take care of myself?

Follow the steps outlined above to treat your rash. In addition, keep the affected skin clean and dry. Keep your fingernails well trimmed and clean. Try not to scratch your skin to avoid an infection.

See your doctor if you develop severe symptoms.

What can be done to help prevent a reaction to poison ivy, sumac, or oak?

Follow these guidelines:

• Know what the plants look like and where they grow so you can avoid them.
• Wear long-sleeved shirts and long pants if you are going to be in an area where these plants grow.
• Within 5 to 10 minutes of contact with the plant, rinse exposed skin thoroughly with soap and water (or just water).
• Be sure to clean under your fingernails.
• Wash clothes and shoes in hot water and detergent to remove any oil that may be on them.
• Give any outdoor pets a bath if you think they have had contact with the plants.