Bullous pemphigoid (BUL-us PEM-fih-goid) is a rare skin condition that causes large fluid-filled blisters. They often appear on the skin near creases, such as the upper thighs and armpits. Sometimes, people get a rash instead of blisters. The affected areas may be painful and are usually very itchy. Blisters or sores also might form in the mouth, but this is rare.
Bullous pemphigoid occurs when the immune system attacks a layer of tissue in the skin. The reason for this immune system response is not well understood. In some people, the condition is brought on by certain medicines.
Bullous pemphigoid often goes away on its own in a few months, but it may take as many as five years to go away for good. Treatment usually helps heal the blisters and prevent new ones from forming.
The condition is most common in people over age 60.