What causes Anorectal abscess?
Last updated September 7, 2026.
**Most anorectal abscesses start when one of the tiny glands inside the anal canal gets blocked and infected, so bacteria multiply and pus collects in the tissue around it.** The picture changes when something else is driving it: Crohn's disease, an anal fissure, a sexually transmitted infection, or injury from trauma, childbirth, or previous surgery can all set one off. Weakened immune defenses from diabetes, HIV, cancer treatment, or long-term steroid use make an abscess more likely and slower to clear. Abscesses that keep coming back, or that sit in unusual places, point toward an underlying condition worth testing for, especially Crohn's disease. Keeping stool soft with fiber, fluids, and prompt treatment of constipation limits irritation of the anal canal, and warm sitz baths ease early soreness. An abscess almost always needs drainage by a clinician, so a firm, swollen, painful lump near the anus is a reason to be seen quickly.
What to do
- Get it drained: A painful, swollen lump near the anus needs a same-day exam, because drainage is the treatment and antibiotics alone rarely fix it.
- Watch for red flags: Fever, chills, spreading redness, trouble passing urine, or pain severe enough to stop you sitting means go to urgent care or the emergency room now.
- Soften your stool: Aim for more fiber, steady fluids, and treat constipation early so hard stool stops irritating the anal canal.
- Use warm sitz baths: Sitting in a few inches of warm water for 10 to 15 minutes a few times a day eases pain before and after drainage.
- Ask about Crohn's: If you have had more than one abscess, or also have diarrhea, weight loss, or blood in stool, ask your clinician about testing for inflammatory bowel disease.
- Manage your risk factors: Keep blood sugar controlled if you have diabetes, and tell your clinician about steroids, chemotherapy, or HIV, since these slow healing.
Related questions
- Can i see what my doctor wrote about me
- How do i find out what my insurance covers
- What age should i start mammograms
- What are clots in period blood