Anal Abscess
Treatment of a collection of pus around the anus, with prompt assessment and appropriate drainage when required
What is anal abscess?
An abscess beside the anus is a collection of pus, and it starts in one of the small glands that drain into the anal canal. The gland blocks, bacteria multiply behind the blockage, and the infection spreads into the fatty tissue around the canal.
It announces itself over a day or two. There is a throbbing pain that builds instead of easing, that is worse sitting down, and that keeps people awake. A tender swelling appears beside the anus, and there is often a fever with it. Some abscesses sit deeper and cannot be felt from outside at all. Those present as severe pain and fever with very little to see, and they need a scan.
The important thing about an abscess is that it is a mechanical problem, not simply an infection. Pus under pressure in a closed space has to be let out. Antibiotics reach the tissue around a collection and not the collection itself, so they may take the edge off and will not resolve it.
What you might notice
- Fever with a painful swelling near the anus
- Pain or itching around the anus
- A lump near the anus
- Discharge or wetness near the anus
How it is diagnosed
Most abscesses are diagnosed by examination alone: the area is red, swollen, hot and exquisitely tender, and the diagnosis is usually obvious within a minute of looking.
If the pain and fever are severe but there is little to see or feel, a doctor will suspect a collection higher up and arrange a scan, an MRI or a CT, to find it. Do not take a normal-looking examination as reassurance if the pain is severe; say so.
If you have diabetes, a suppressed immune system, or pain out of proportion to the findings with skin changes spreading quickly, this is treated as urgent. Those are the circumstances in which an anorectal infection can spread fast, and they change the timetable from days to hours.
Recovery
The relief after drainage is immediate and dramatic. This is one of the few operations where people feel better the moment they wake up.
The wound is left open on purpose so it drains instead of sealing over a pocket of infection, and it heals from the base upwards over two to four weeks. It needs showering and a simple dressing, not packing in most cases. Warm baths help. You will usually be back at work within a few days.
Expect a follow-up appointment several weeks later even if everything has healed. That visit is looking for a fistula, and it is the point of the appointment.
If it is left untreated
An abscess that is not drained keeps building pressure and spreading through the tissue planes around the anus, which is more painful and turns a small drainage into a larger one.
Some burst on their own and discharge, and the pain settles. That is not the same as being better: what is left is an unhealed tract that becomes a fistula, and the tract will refill.
The reason this is urgent and not merely uncomfortable is the small number of cases that spread rapidly into the surrounding tissue. In someone with diabetes or a weakened immune system that can become life-threatening within a day. Spreading redness, severe pain, a high fever or feeling generally unwell are reasons to be seen the same day and not to wait for an appointment.
Questions about anal abscess
Can antibiotics clear it instead of surgery?
No. An abscess is pus under pressure in a closed space, and antibiotics reach the tissue around it and not the collection itself. They may take the edge off the surrounding inflammation, which sometimes makes things seem better for a day or two, and the collection is still there. It has to be drained. Antibiotics are given alongside drainage where there is spreading infection, diabetes or a weakened immune system, and not instead of it.
How urgently do I need to be seen?
Promptly, and the same day if the pain is severe, if you have a fever, if the redness is spreading, or if you feel generally unwell. It is more urgent still if you have diabetes or a suppressed immune system, because those are the circumstances in which an infection around the anus can spread quickly through the tissue and become dangerous within a day. Pain that is worse than the examination findings suggest is a reason to push, not to wait.
Why has a fistula formed afterwards?
Because the abscess started in a gland inside the anal canal, and after the pus drains the route it took to the skin can stay open as a lined tract. That happens after roughly a third of these abscesses, and it is not a sign anything went wrong with the drainage. It is why you are given a follow-up appointment weeks later even if the wound has healed. That visit is looking for exactly this.
Other proctology treatments
Treatment for swollen veins in the anus or lower rectum, ranging from lifestyle measures to minimally invasive or surgical care
Day CareManagement of a painful tear in the anal lining, with treatment chosen according to severity and duration
Day CareTalk to a care coordinator about anal abscess
Leave a number and a care coordinator calls you back with what the treatment involves and which hospital it would be at. They book a consult only if you want one