Can diarrhea cause anal fissures?

No: Anal fissures are almost always caused by constipation or anal distension (such as with anal intercourse or anal manipulation). Fissures can also be associated with hypertonic anal sphincter. The treatment centers around trying not to stretch the anus too much: stool softners, less aggressive sexual practices and sometimes relaxation of the anal sphincter by surgery or Botox injection.

No: Anal fissures can occur secondary to constipation. If someone has long standing constipation and they use laxatives , they can sometimes develop diarrhea due to laxatives . There can be other reasons for diarrhea like inflammatory bowel disease or bowel cancer which would need to be ruled out first in such cases .