Blisters may develop from diseases that cause your body to attack your own skin (autoimmune diseases), such as:

• Pemphigus, an uncommon, sometimes fatal disease. Blisters of varying sizes break out on the skin, the lining of the mouth, the vagina or penis, and other mucous membranes. Treatment includes medication to suppress the immune system and, sometimes, a plasma exchange procedure (plasmapheresis).
• Bullous pemphigoid, a less dangerous disease than pemphigus. Blisters are itchy, hard, and tight, and the skin between the blisters is red and may be swollen. Unlike in pemphigus, blisters do not form in the mouth. Treatment involves medication to suppress the immune system.
• Dermatitis herpetiformis, a chronic inflammatory disease that may be caused by a sensitivity or allergy to gluten. Clusters of small blisters and hive-like swellings that itch and burn break out on the skin of the elbows, knees, buttocks, lower back, and back of the head. Occasionally blisters form on the face and neck. Treatment includes taking medication and removing all foods that contain wheat, rye, barley, and oats from the person's diet.