Poison ivy is caused by a reaction to an oily substance from the leaves, stems, and roots of poison ivy. This oily substance is called urushiol.

At least 50 percent of people who come in contact with poison ivy develop a rash. The most dangerous exposure to poison ivy is when someone burns the plant and inhales the smoke. This can cause an allergic reaction which can sometimes be deadly.

Signs and symptoms of poison ivy include redness, itching, swelling and blisters. Many times the rash looks like a straight line due to the way the plant rubs up against you. The rash may develop 24 to 48 hours after exposure. Without treatment, the rash may last as long as two to three weeks. The severity of the rash depends upon how much contact was made with urushiol. Your skin must come in contact with the oil, it can not be spread from person to person without exposure to the oil.

You should contact your doctor when the reaction is widespread or severe. If it affects the genitals or face you should see the doctor. If you develop a fever above 100, or if the rash appears to be infected, you should consult your doctor.

You can develop poison ivy from direct contact, touching contaminated objects, or inhaling smoke from burning plants. You should wash your hands or clothes immediately upon exposure to poison ivy.

You may not need to see your doctor every time you are exposed. However, if you do see your doctor he will examine you and ask you questions about possible exposure to get the diagnosis correct. In more severe cases steroids may be prescribed to shorten the duration and also reduce the severity of the rash. Also antibiotics may be used if the rash looks infected. There are many things that can help the itching like OTC steroid cream, calamine lotion, Benadryl, cool baths containing Aveeno bath and cool compresses.

Prevention is always the key in any illness. Avoid the plants and know what they look like. Remove or kill the plants with approved weed killer. Do not burn the plants. Wash your skin off when exposed. Wear long sleeves and pants when working around the plants. And wash clothes immediately when done. These tips will greatly reduce the likelihood of you developing the rash.