Blisters

Blisters are small pocket of fluid within the upper layer of the skin. Most blisters are filled with a clear fluid called serum or plasma. However, blisters can be filled with blood (known as blood blisters) or with pus (if they become infected).

Causes

It is a result of friction (rubbing), burning, freezing, and chemical exposure.

Symptoms

If they are large they can be painful.