A poison ivy rash is an allergic reaction to an oily sap called urushiol that is produced by poison ivy, poison oak, and sumac plants. When your skin comes into contact with this substance, it can provoke a reaction that results in an itchy, red rash on the part of the skin where you touched the sap. You can also have an allergic reaction to urushiol if you touch a surface that came into contact with the sap, or if you breathe in smoke from burning these plants.
Poison ivy, poison oak, and sumac are very common plants in North America. Poison ivy and poison oak have three leaflets, clusters of leaves at the ends of stems. Sumac has clusters of leaves that commonly appear in pairs. Outdoor activities can increase your risk of coming into contact with these plants.
Common symptoms of a poison ivy rash include:
- Redness
- Swelling
- Itching
- Blistering
- Breathing difficulty (if you inhale smoke from burning poison ivy)
The symptoms of a poison ivy rash will begin to appear within a day of contact with the plant. The severity of the rash usually depends on how much urushiol came into contact with your skin but can be made worse by scratching.
If you suspect you may have touched poison ivy, poison oak, or sumac, it is recommended that you wash the area right away. This can help prevent urushiol from spreading to your clothes, or other parts of your body, and may minimize rash symptoms.
The best way to prevent a poison ivy rash is to stick to cleared paths while hiking or camping, and wear protective clothing while you do outdoor activities. Wearing socks, long pants, and long sleeves while camping or hiking can reduce the risk of touching urushiol sap with your skin. If you are gardening, it is recommended that you wear heavy gloves to protect your hands.
Most poison ivy rashes are relatively mild and require little medical treatment. If your blisters begin to ooze pus, or if you experience difficulty breathing, talk to your health care provider for treatment.