The urushiol oils in the stems, roots, berries, and leaves of poison ivy plants cause an allergic rash, a type of contact dermatitis. The oil is thick and attaches to various surfaces including clothing, skin, and pet's fur. The rash itself is not contagious -- the blister sacs that may form during a breakout do not contain urushiol. It is the passing of the oil from one surface, or one person, to another that causes and prolongs the rash. There is a range of symptoms and treatments for poison ivy rash -- people generally treat poison ivy with home remedies, and it heals after two or three weeks.
Redness as a symptom is not an ideal indicator for poison ivy, as many things can cause redness, including sunburn and other allergies one may contract when out in nature. As a response to fight off irritants and help the body start healing, blood rushes to the skin's surface. Redness can become uncomfortable if this reaction persists for an extended period. Redness may be caused by poison ivy if the affected person notices other related symptoms.
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