In Henoch-Schonlein purpura, some of the body's small blood vessels become inflamed, which can cause bleeding in the skin, joints, abdomen and kidneys. Why this initial inflammation develops isn't clear, although it may be the result of an overzealous immune system responding inappropriately to certain triggers.

Nearly half the people who have Henoch-Schonlein purpura developed the disease after an upper respiratory infection, such as a cold. Infectious triggers may include chickenpox, strep throat, measles and hepatitis. Other triggers may include certain medications, food, insect bites or exposure to cold weather.

Jul. 31, 2013