An anal abscess can have many different causes. These include: • An infected anal fissure (tear) • Sexually transmitted infections • Blocked anal glands • HIV and other forms of immune suppression • Diabetes • Anal sex • Chronic or severe constipation or diarrhea • Steroid drug use, including prednisone • Chemotherapy • Hidradenitis suppurativa, a rare skin condition Risk factors for anal abscesses include: • Colitis • Inflammatory bowel diseases such as: • Crohn's disease • Ulcerative colitis • Diabetes • Diverticulitis • Pelvic inflammatory disease • Being the receptive partner in anal sex • Use of medications such as prednisone