Poison ivy, as well as poison oak and sumac, contains an oil called urushiol, which when it comes in contact with skin, causes an allergic reaction in about 85 percent of the population. The subsequent rash that develops will only appear where the skin came in contact with the plant's oil -- and luckily, it isn't contagious, but it can spread through indirect contact (such as petting a dog that has run through poisonous plants).
Symptoms of a poison ivy rash may include:
- Itchy skin
- Redness or red streaks
- Small bumps or hives
- Blisters that drain fluid when popped
The only way to avoid developing the rash is to avoid contact with these poisonous plants, but wearing clothing that covers a good amount of skin will help reduce your risk. The American Academy of Dermatology recommends home treatment for mild cases, including cool showers and oatmeal baths. If itching and swelling become moderate to severe, prescription medications can be used to reduce symptoms.