I frequently get blood blisters in my mouth, usually on the inside of my cheeks and sometimes under my tongue. Tonight I had a very large one under my tongue that was approximately 1/2" long and at least 1/4" wide.

Can you tell me what could be causing these blood blisters? Can they be caused by a vitamin deficiency? I do drink a lot of hot water instead of drinking coffee or tea. Could this cause the blood blisters? I have been drinking hot water, though, for years and the problem with the blisters has just been happening this past year.