Internal hemorrhoids occur at the junction of the anus and rectum and are covered with mucous membrane.
External hemorrhoids occur just outside the anus and are covered with skin.
On occasion an internal hemorrhoid may prolapse, or protrude, to the outside, cutting off the blood supply. A number of treatments are available for internal hemorrhoids. Hemorrhoids can occur at any age, often without apparent cause. Causes may include constipation, pregnancy, liver disorders, rectal tumors, and the repeated use of laxatives. Hemorrhoids can cause itching and burning and may bleed during a bowel movement.