A blister is a raised portion of skin filled with fluid. The clear watery liquid inside a blister is called serum. It leaks from neighboring tissues in response to injured skin. A blood blister is filled with blood rather than serum.
What causes blisters?
Blisters can be caused by many things. One common cause is friction. Blisters from friction occur when vesicles develop from rubbing which causes layers of skin to separate and fill with fluid. Blisters can also be caused by infections, burns, extreme cold, reactions to irritants, drug reactions and skin conditions.
What are the symptoms?
A blister presents as a fluid filled shell on top of the skin that is painful and can become infected.
How are blisters diagnosed?
Blisters are diagnosed by history and visual examination. Depending on the severity and cause of the blister, many simple blisters can be successfully treated at home. However, larger, more severe or unexplained blisters should always be examined by a dermatologist.