A poison ivy rash is not contagious and coming into contact with a blister or its fluid content will not transmit the rash to another person. What causes the rash is the oil called urushiol. Plants such as poison ivy, sumac and poison oak contain this chemical which causes allergic reactions in people, states Mayo Clinic.
Urushiol resin also is transmitted from the plant to clothing, animal fur or other items. People can get a poison ivy rash if they come into contact with a contaminated source. People can also be affected with a poison ivy rash if they breathe in smoke from a plant that is burned. The substance urushiol can remain active for more than a year on contaminated objects, reports the Colombia University Medical Center's Department of Dermatology.
The symptoms of a poison ivy rash are itchy skin, bumps, blisters that exude a fluid, inflammation near the affected rash site and redness. If a person has a severe allergic reaction, then he may have serious symptoms, such as breathing problems and inflammation of the face or mouth areas. These symptoms require prompt medical attention.
In most people, the rash resolves within 10 days to 3 weeks, states WebMD. People with severe rashes that cover a large portion of the body should see a doctor for treatment such as steroid medication.