Bulla

Bulla is a large blister filled with clear fluid that forms on the skin. It is usually caused by a burn or an allergic reaction. The blister can range from a few millimeters to several centimeters in size. It appears as a raised, fluid-filled bubble on the skin and can be painful. Bullae usually develop over a few hours and can last for days or weeks before healing. They can manifest differently depending on the cause, such as in the case of an allergic reaction.