In short
A perianal abscess is a collection of pus beside the anus, usually from a blocked and infected anal gland. It causes a constant, throbbing, worsening pain — unlike a fissure, it does not ease between bowel movements — often with swelling, redness and fever. It needs draining, not waiting.
Why antibiotics alone will not fix it
Antibiotics reach an abscess cavity poorly, because there is no blood supply inside a collection of pus. They may take the edge off the surrounding inflammation, which sometimes makes it feel briefly better, but the pus stays where it is and the pressure keeps building.
An abscess is drained. That is the treatment. Antibiotics are an adjunct for surrounding cellulitis or for patients with diabetes or reduced immunity.
Why it should not wait
Untreated, the infection spreads through the tissue planes around the anus, the cavity gets larger, and more tissue is destroyed. A small abscess drained early is a minor procedure. A large or deep one that has been left is not.
In people with diabetes or reduced immunity, and rarely in anyone, perianal infection can escalate into a severe spreading infection. That is uncommon but it is the reason this is treated as urgent rather than routine.
What drainage involves
A small incision at the point of maximal swelling releases the pus, the cavity is cleaned out, and the wound is left open so it heals from the bottom up rather than sealing over infection. Relief is usually immediate and dramatic — the pain of an abscess is pressure, and releasing the pressure ends it.
The fistula question
A meaningful proportion of perianal abscesses are followed by a fistula, because the tract the infection took to reach the skin stays open. This is not a complication of the drainage — it is the natural history of the disease.
It is why follow-up after drainage matters. Persistent discharge from the site weeks later usually means a fistula has formed, and that is dealt with as a separate, planned procedure once things are quiet.
Go to an emergency department if
- You have a high fever, rigors, or feel very unwell
- The redness is spreading rapidly across the skin
- The pain is severe and out of proportion to what you can see
- You are diabetic or immunosuppressed and have any perianal swelling with fever
- There is any skin discolouration, blistering or crackling under the skin — that needs immediate assessment
These are the symptoms that should not wait.
Common questions
- Can an abscess burst and heal on its own?
- It can burst, and the pain will improve when it does. But the cavity and the tract usually remain, which is why so many go on to become fistulas. Spontaneous drainage is not the same as treatment.
- Is drainage done under general anaesthetic?
- It depends on the size and depth. A small superficial abscess can be drained under local anaesthetic; a larger or deeper one is better done under anaesthesia so the cavity can be cleaned out properly.
- Will I definitely get a fistula afterwards?
- No — many people heal completely. But a significant minority develop one, which is why a follow-up appointment after drainage is part of the plan rather than optional.
General information only. Anorectal symptoms overlap and only an examination can tell them apart — please do not use this page to diagnose yourself.