This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Hypersensitivity vasculitis is an extreme reaction to a drug, infection, or foreign substance that leads to inflammation and damage to blood vessels of the skin. Signs and symptoms may include purple-colored spots and patches on the skin; skin lesions on the legs, buttocks, or trunk; blisters on the skin; hives (urticaria); and/or open sores with dead tissue (necrotic ulcers). This condition is caused by an allergic reaction to a drug or other foreign substance. This condition usually goes away over time; but on occasion, people can have repeated episodes.
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