Bullous pemphigoid (BUL-us PEM-fih-goid) is a rare skin condition that causes large, fluid-filled blisters on areas of skin that often flex — such as the lower abdomen, upper thighs or armpits. Bullous pemphigoid is most common in people older than age 60.
Bullous pemphigoid occurs when your immune system attacks a thin layer of tissue below your outer layer of skin. The reason for this abnormal immune response is unknown, although it sometimes can be triggered by taking certain medications.
Treatment usually includes corticosteroids, such as prednisone, and other drugs that suppress the immune system. Bullous pemphigoid can be life-threatening, especially for older people who are already in poor health.