What is a blister?
A blister is a raised area containing fluid under the top layer of skin. Blisters are usually circular in shape. The fluid that forms underneath the skin can be blood or serum, the clear liquid portion of the blood. These fluids sometimes collect in an area of damaged cells and form a blister.
What causes a blister?
Blisters can form as a reaction to trauma to the skin or certain skin diseases, including: