Anal Abscess and Fistula
These two conditions are different stages of the same underlying process — a blocked, infected anal gland — and both are commonly mistaken for hemorrhoids at first. Unlike most of what’s on this site, one of them (an abscess) is a genuine same-day medical situation, not something to research and monitor at home.
- An abscess is an active infection causing a painful, often rapidly worsening swelling — it needs to be drained, usually the same day.
- A fistula is what can develop afterward: a persistent small tunnel that causes recurring drainage and swelling, and doesn’t heal without a procedure.
- Neither resolves with hemorrhoid creams, sitz baths, or waiting.
Which one matches what you’re experiencing?
A new, painful, firm swelling that’s getting worse — possibly with fever → this sounds like an active abscess. See Anal abscess: a surgical emergency for what to do, and how urgently.
Ongoing or recurring drainage from a small opening in the skin, sometimes with swelling that comes and goes → this sounds more like a fistula, often following a previous abscess. See Anal fistula for what it is and what treatment involves.
Not sure, or symptoms that don’t clearly match either → the broader differential diagnosis overview covers the full range of possibilities, including conditions that share some features with these two.
Why these are grouped together
An abscess and a fistula are two points on the same timeline: an abscess is the acute infection, and a fistula is the persistent tunnel that can be left behind after that infection is drained (whether by a clinician or on its own). Understanding one helps make sense of the other, which is why they’re presented together here.
This page is a short index — see the two linked articles for full detail on each condition.