Overview
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.
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Symptoms
Signs and symptoms of a poison ivy rash include:
- Redness
- Itching
- Swelling
- Blisters
- Difficulty breathing, if you’ve inhaled the smoke from burning poison ivy
Poison ivy rash often appears in a straight line because of the way the plant brushes against your skin. But if you develop a rash after touching 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.
When to see a doctor
Seek emergency medical attention if:
- You inhaled the smoke from burning poison ivy and are having difficulty breathing
See your doctor if:
- The reaction is severe or widespread
- Your skin continues to swell
- The rash affects your eyes, mouth or genitals
- Blisters are oozing pus
- You develop a fever greater than 100 F (37.8 C)
- The rash doesn’t get better within a few weeks
