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Poison ivy, poison oak, and poison sumac are native American plants. These plants cause an allergic reaction in most people who are exposed to them. To be allergic to poison ivy, you must come in contact with the plant once for sensitization to the oils to happen. This means that next time contact with the plant happens, a reaction may happen 24 to 72 hours after exposure. An allergic reaction can’t be spread from one person to another by touching the blisters or from the fluid inside the blisters. But, it can be spread if the plant oils remain on the skin, clothes, or shoes.
The resin in the plants contains an oily substance called urushiol. Urushiol is easily passed from the plants to other objects. These include tools and animals. This chemical can remain active for a year or longer. It is important to know that the oils can be passed from clothing, pets, or smoke from a burning plant.
The allergic reaction to poison ivy, poison oak, or poison sumac is usually contact dermatitis. This may happen 24 to 72 hours after exposure. The dermatitis is characterized by bumps and blisters that itch. Sometimes, swelling happens in the area of contact. Eventually, the blisters break, ooze, and then crust over.
Diagnosis is usually based on a medical history and physical exam.
There is no cure for the reaction once the rash starts. Avoiding the plants is the best treatment. It is very important to learn what the plants look like and to not touch them.
If you have already come in contact with the plants, remove the oils from your skin as soon as possible. Do this by washing with ordinary soap. Repeat the cleaning with the soap 3 times. There are also alcohol-based wipes that help remove the oils. Also wash all clothes and shoes because the oils can remain on them.
For the itching, your healthcare provider may recommend over-the-counter creams, such as calamine lotion. He or she may also recommend bathing in a baking soda or colloidal oatmeal bath. These can be bought at your local drugstore. Sometimes your healthcare provider will prescribe a topical cortisone containing cream or medicine to take by mouth for the itching. Oral steroids are commonly used along with oral antihistamines.
Tell your healthcare provider if you have a temperature over 100°F (38°C) and the blisters and rash are on your face, in your eyes, near your genitals, or all over your body. After a medical history and physical, your healthcare provider may prescribe a steroid cream, pills, or injection to help with the swelling and itching.
In some cases, a severe reaction that causes swelling or trouble with breathing or swallowing may happen. If this happens, get treatment right away. This is an emergency.
Be sure to follow recommendations for preventing an allergic reaction to these plants by avoiding exposure.
While most allergic reactions to poison ivy, poison oak, or poison sumac are easily managed at home, you should call your healthcare provider right away if:
Call 911 or go to the emergency room if:
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