Poison ivy, poison oak and poison sumac are plants that produce an oil (urushiol) that causes an allergic reaction among humans. Some people are allergic to other plants species such as yarrow, garlic mustard, or lilies. Symptoms include itching and burning skin, redness, swelling and sometimes even blisters or hives that appear in the area that came into contact with the plant. The rash begins one to two days after exposure. The inflammation is a form of contact dermatitis, an allergic reaction to an allergen that comes into direct contact with the skin.
How can poison ivy be treated?
Treatment for poison ivy, poison oak and poison sumac is designed to relieve the itching and may include oral antihistamines and cortisone creams (either over-the-counter or prescription). These treatments need to be applied before blisters appear or after the blisters have dried up to be effective. In severe cases, oral steroids, such as prednisone, may be prescribed.