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Perianal Abscess in Singapore: A Painful Anal Lump

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Written & reviewed by the BestDoctors.sg editorial team · Last updated 25 Aug 2026 · General information, not medical advice

A perianal abscess is a painful, pus-filled collection (a boil-like lump) near the anus, and it is the acute infection that often comes before an anal fistula. Most start when a small gland just inside the anus becomes blocked and infected, and pus collects in the surrounding tissue. The key point: an abscess usually needs prompt surgical drainage — it will not reliably clear with antibiotics alone — so it should be seen early rather than waited out.

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In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.

High fever and chills, feeling very unwell, rapidly spreading redness, or severe worsening pain can signal spreading infection or sepsis — call 995 or go to A&E. People with diabetes or weakened immunity should seek care especially early.

What it is

Around 90% of anal abscesses arise from these internal anal glands. The most common location is just under the skin beside the anus (perianal), but deeper types exist, and an abscess that spreads part-way around the anus is called a “horseshoe” abscess. Because a deeper abscess can cause pain and pressure with little visible on the skin, it is worth seeing a doctor for unexplained, persistent anal pain even without an obvious lump.

Causes and risk factors

The usual cause is a blocked and infected anal gland. Inflammatory bowel disease, especially Crohn’s disease, is an important risk factor — an abscess or fistula can be the first sign of Crohn’s — along with diabetes and a weakened immune system from HIV, cancer treatment or long-term steroids. Other contributors include smoking, chronic diarrhoea or constipation, anal trauma, an infected anal fissure, diverticulitis, some sexually transmitted infections, and pregnancy.

Symptoms

There is usually constant, throbbing pain near the anus, often worse when sitting or during a bowel movement, with a swollen, red, tender lump beside the anus and warmth of the surrounding skin. Pus may discharge (which often eases the pain), and there may be some rectal bleeding, feeling generally unwell, fever or chills. Occasionally there are urinary symptoms or a sense of lower rectal pressure.

Red flags

A perianal abscess needs prompt drainage — do not “wait it out.” Seek urgent or emergency care for a high fever and chills, feeling very unwell, rapidly spreading redness or swelling, or severe and worsening pain, which can signal spreading infection or sepsis. A rare but life-threatening spreading infection of the perineum (Fournier’s gangrene / necrotising soft-tissue infection) is a surgical emergency. In Singapore, call 995 or go to the nearest A&E for a high fever with rapidly spreading redness, severe pain, or signs of serious illness, and people with diabetes or a weakened immune system are at higher risk and should seek care especially early.

How it is assessed and treated

Diagnosis is mainly clinical — a history plus examination of the perianal area, with a digital rectal exam that may be very painful, and most abscesses are diagnosed and treated on clinical findings alone. Imaging (endoanal ultrasound, MRI or CT) is reserved for deep, complex, recurrent or uncertain cases, or when Crohn’s is suspected. A colorectal or general surgeon manages it. Surgical drainage (incision and drainage) is the mainstay — an opening is made to let the pus out, often under local anaesthetic in a day-surgery setting, with larger or deeper abscesses needing theatre and a short hospital stay for dressings. Antibiotics alone are a poor substitute for drainage and are added only in specific situations such as diabetes, weakened immunity, spreading cellulitis or certain heart conditions; this guide gives no doses. Supportive care after drainage includes warm sitz baths, adequate fibre and fluids, stool softeners and pain relief, and any underlying condition such as Crohn’s or diabetes is treated. If an abscess keeps coming back, a fistula is often the reason and needs separate treatment.

After drainage and prevention

Recovery is usually straightforward with good wound care. Warm sitz baths several times a day, especially after bowel movements, keep the area clean and comfortable, and keeping stools soft with fibre, fluids and, if advised, a stool softener reduces straining while the wound heals; the wound is often left open to heal from the base up, so follow the advice you are given on dressings. Watch for the abscess recurring or for a small opening that keeps draining pus, which suggests a fistula, and report it. Keeping diabetes well controlled and not smoking help healing and reduce recurrence, and prompt attention to any future painful anal lump means it can be drained before it becomes a bigger problem. If drainage wounds are slow to heal or a small opening keeps weeping, mention it at follow-up, as this often points to a fistula that needs its own treatment rather than a wound that will simply close on its own. Keeping stools soft with fibre and fluids in the weeks after drainage makes bowel movements far less painful while the area heals.

When to see a doctor

See a doctor promptly for a painful lump, swelling, redness or discharge near the anus, especially with fever, and go to A&E or call 995 for a high fever, spreading redness, severe pain or feeling very unwell.

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Sources

General information only. This guide is general information about a colorectal or anal condition and is not a diagnosis or personalised medical advice. See a doctor or colorectal surgeon for assessment. Do not assume rectal bleeding, an anal lump, a non-healing sore, or a change in your bowel habit is “just piles” — these must be checked to exclude bowel or anal cancer. Seek urgent care for a painful, spreading anal swelling with fever, or severe abdominal pain with vomiting and not passing stool or wind (possible obstruction); call 995 for a high fever with rapidly spreading redness or severe illness.

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Frequently asked questions

Can a perianal abscess go away on its own?

Usually not. An abscess is a trapped pocket of pus that typically needs to be drained by a doctor. Even if it bursts on its own, drainage is often incomplete and it can come back, so see a doctor.

Will antibiotics alone cure it?

Usually not. Drainage is the main treatment; antibiotics on their own do not reliably clear the pus. Doctors add antibiotics in certain situations, such as diabetes, weakened immunity or spreading skin infection.

Is a perianal abscess an emergency?

It needs prompt attention. It becomes an emergency if you have high fever, chills, rapidly spreading redness, or severe worsening pain, which can mean the infection is spreading. In Singapore, call 995 or go to A&E.

Will I definitely get a fistula afterwards?

Not everyone does. Studies suggest roughly a third to a half of people who have an anal abscess later develop a fistula. If pus keeps draining from a small opening in the skin, tell your doctor.

Does drainage hurt and how long is recovery?

The drainage itself is done with numbing (local anaesthetic) or general anaesthesia, and pain often eases once the pus is released. Recovery involves sitz baths, pain relief and wound care; your surgeon will advise on time off work.