Dermatitis herpetiformis is a long-term (chronic), recurring skin rash with many small fluid-filled skin sores (blisterlike sores). After healing, the sores often leave discolored areas and sometimes scarring.

The cause of dermatitis herpetiformis is not known. But almost all people with dermatitis herpetiformis also have celiac disease, which interferes with a person's ability to eat foods containing gluten—a form of protein found in some grains (notably wheat, barley, and rye). Celiac disease is considered a type of immune disorder and is treated by adopting a strict gluten-free diet. This diet is also used to treat dermatitis herpetiformis.