No, you cannot get internal or external hemorrhoids from a dirty toilet seat. The force of a hard bowel movement passing through the anal canal and damaging the tissue causes hemorrhoids. Some physicians theorize that deterioration of the supporting tissue causes the hemorrhoidal tissue to slide into the anal canal. Elevated pressure from the anal sphincter either precedes the development of an enlarged hemorrhoid or is caused by an enlarged hemorrhoid.
Insufficient fiber in a patient’s diet may contribute to hemorrhoids. Sitting for extended periods of time either on the toilet or hard chair may irritate the soft tissues just inside the anus. Excessive straining with a difficult bowel movement may pull or tear at the delicate internal tissues just inside the opening to the rectum causing damage. Females often develop hemorrhoids during pregnancy. By pressing on veins in the anal canal, tumors in the pelvis may agitate hemorrhoidal tissues.