Poison ivy rash is caused by an allergic reaction to an oily resin called urushiol (u-ROO-she-ol). This oil is in the leaves, stems and roots of poison ivy, poison oak and poison sumac.
Wash your skin right away if you come into contact with this oil, unless you know you're not sensitive to it. Washing off the oil may reduce your chances of getting a poison ivy rash. If you develop a rash, it can be very itchy and last for weeks.
You can treat mild cases of poison ivy rash at home with soothing lotions and cool baths. You may need prescription medication for a rash that's severe or widespread — especially if it's on your face or genitals.
Signs and symptoms of a poison ivy rash include:
- Difficulty breathing, if you've inhaled the smoke from burning poison ivy
Often the rash looks like a straight line because of the way the plant brushes against your skin. But if you come into contact with a piece of clothing or pet fur that has urushiol on it, the rash may be more spread out. You can also transfer the oil to other parts of your body with your fingers. The reaction usually develops 12 to 48 hours after exposure and lasts two to three weeks.
The severity of the rash depends on the amount of urushiol that gets on your skin. A section of skin with more urushiol on it may develop a rash sooner.
Your skin must come in direct contact with the plant's oil to be affected. Blister fluid doesn't spread the rash.
Poison ivy rash is a type of allergic contact dermatitis caused by an oily resin called urushiol. It's found in the leaves, stems and roots of poison ivy, poison oak and poison sumac. This resin is very sticky, so it easily attaches to your skin, clothing, tools, equipment and pet's fur. You can get a poison ivy reaction from:
- Direct touch. If you touch the leaves, stem, roots or berries of the plant, you may have a reaction.
- Touching contaminated objects. If you walk through some poison ivy and then later touch your shoes, you may get some urushiol on your hands, which you may then transfer to your face or body by touching or rubbing. If the contaminated object isn't cleaned, the urushiol on it can still cause a skin reaction years later.
- Inhaling smoke from the burning plants. Even the smoke from burning poison ivy, poison oak and poison sumac contains urushiol and can irritate or harm your nasal passages or lungs.
A poison ivy rash itself isn't contagious — blister fluid doesn't contain urushiol and won't spread the rash. And you can't get poison ivy from another person unless you've touched urushiol that's still on that person or his or her clothing.
You generally won't need to see your doctor for a poison ivy rash. If you do visit your doctor, he or she will be able to diagnose your rash by looking at it. No further testing is needed.
Poison ivy treatments are usually limited to self-care methods. And the rash typically goes away on its own in two to three weeks.
If the rash is widespread or results in a large number of blisters, your doctor may prescribe an oral corticosteroid, such as prednisone. If a bacterial infection has developed at the rash site, your doctor may give you a prescription for an oral antibiotic.