What is Blister?
[[File:Blister roundup.jpg|thumb|Blister caused by a chemical burn]] A '''blister''' is a small pocket of [[fluid]] in an upper layer of the skin caused by [[friction]], [[burn]]ing or [[freezing]]. Most blisters are filled with a clear fluid called [[serum]] or [[Blood plasma|plasma]] (blister water). Some blisters, however, are filled with [[blood]]; they are called [[Blood blister|blood blisters]]. == Blood blisters == A blood blister is a pocket of [[fluid]] filled with [[blood]]. [[Category:Medical signs]]