Infection of an anal fissure (cleft or slit), sexually transmitted infections, and blocked anal glands are common causes of anorectal abscesses. Abscesses may occur in an area that is easily accessible for drainage, or higher in the rectum. Deep rectal abscesses may be caused by intestinal disorders such as Crohn's disease or diverticulitis.

High risk groups include diabetics, immunocompromised patients, people who engage in receptive anal sex, and patients with inflammatory bowel disease.

Superficial perianal abscesses are not uncommon in infants and toddlers who are still in diapers and have a history of anal fissures. The abscess often appears as a swollen, red, tender lump at the edge of the anus. The infant may be fussy from discomfort but there are generally no other associated systemic symptoms. Surgical drainage and antibiotics provide prompt relief in such cases.