What Causes Anal Pain?

An Overview — Two Key Patterns

The most useful question to ask yourself is: does the pain happen when you go to the toilet, or is it there all the time regardless?

Pain that flares up with a bowel motion — sharp, burning, or tearing during or just after — is most likely coming from the anal canal itself: a fissure (a small tear), a thrombosed haemorrhoid (a blood clot), or occasionally an early abscess. Pain that's there all the time — a constant ache, worse when sitting, or waking you at night — suggests something deeper: an abscess, a fistula (a small tunnel from an infected gland), or a functional problem with the pelvic floor muscles.

Anal Fissure — The Classic Pain With Bowel Motions

An anal fissure is a small tear in the lining of your anal canal — the short passage that stool passes through. It's the most common cause of severe pain with bowel motions, and it almost always occurs in the same spot (the back of the passage). The pain is sharp, burning, or tearing — many people describe it as "razor blades" or "broken glass." It starts as the motion passes through and can then ache for anything from 20 minutes to several hours afterwards. Bright red blood on the toilet paper is also common.

Here's why it becomes chronic: the tear causes the sphincter muscle around the anus to go into spasm. That spasm reduces blood flow to the area. Reduced blood flow means the wound can't heal. And every bowel motion re-tears it. Without treatment, this cycle keeps going indefinitely.

Treatment focuses on relaxing the sphincter to break the cycle: topical diltiazem or GTN cream, Botox injection, or in resistant cases, a small operation called lateral internal sphincterotomy. See our article on why anal fissures won't heal for more detail.

Thrombosed External Haemorrhoid

A thrombosed external haemorrhoid is a blood clot that forms in a small vein just outside the anal opening. It typically comes on suddenly — you might go to bed feeling fine and wake up with a painful, firm, blue-purple lump that wasn't there before, often after a period of straining or prolonged sitting. It's alarming but not dangerous.

The pain is constant (not just during bowel motions) but gets worse when you go to the toilet, sit down, or walk. It's usually worst for the first couple of days and then gradually eases over 2–3 weeks. If you're seen within the first 72 hours, a minor procedure under local anaesthetic to drain the clot gives rapid relief. After that, the pain is already settling and warm sitz baths and pain relief work well.

Proctalgia Fugax — The Mysterious Rectal Spasm

Proctalgia fugax means "fleeting rectal pain" — and that's exactly what it is. It's a sudden, severe cramping or stabbing pain deep inside the bottom that comes from nowhere, lasts seconds to a couple of minutes, and then disappears completely. It most often happens at night and can jolt you awake. Most people have fewer than six episodes a year.

The cause is thought to be a spontaneous spasm of the internal sphincter or puborectalis muscle (part of the pelvic floor). No structural problem is found on examination. It's more common in younger adults and has links to stress and anxiety. It's not dangerous and doesn't need investigation beyond ruling out other causes.

For most people, reassurance is all that's needed. For frequent or severe episodes, options include inhaled salbutamol (a reliever inhaler, which can abort an attack), topical diltiazem, or Botox. It feels far worse than it is.

Perianal Abscess — Constant Throbbing Pain

A perianal abscess is a collection of pus that forms in the soft tissue around the anus, usually from a blocked and infected anal gland. Unlike fissure pain, the pain of an abscess doesn't come and go with bowel motions — it's there all the time. A constant, throbbing ache that gets worse when you sit, walk, or try to go to the toilet. Fever and feeling generally unwell are also common.

On examination, there's usually a tender, warm, swollen lump near the anus. Smaller or deeper abscesses may not be as obvious. The only effective treatment is surgical drainage under anaesthetic — antibiotics alone won't resolve it. After drainage, roughly 30–50% of perianal abscesses go on to form a fistula-in-ano (a small tunnel that may need further treatment).

Fistula-in-Ano

A fistula-in-ano is a small tunnel that connects the inside of the anal canal to the skin around the outside. It almost always develops after a previous perianal abscess. The main symptom is a chronic discharge — pus, mucus, or blood — from a small opening near the anus, sometimes with intermittent pain when the opening blocks and a secondary abscess forms.

Most fistulae need surgery to fix. The approach depends on how close the tunnel runs to the sphincter muscles — a simple fistulotomy (opening up the tract) works for shallow fistulae; deeper ones need more careful techniques like seton insertion or an advancement flap to preserve the muscle.

Levator Ani Syndrome and Coccydynia

Levator ani syndrome feels like a persistent dull pressure or ache deep inside the rectum — many people describe it as "sitting on a ball" or a constant feeling of fullness. It's typically worse with prolonged sitting and often better when you get up and walk around. It's thought to come from tension or spasm in the levator ani — the hammock of muscles that forms your pelvic floor. On examination, the levator muscle is tender when pressed. Treatment focuses on pelvic floor physiotherapy (the main treatment), biofeedback, muscle relaxants, and occasionally Botox.

Coccydynia is pain from the tailbone — the small bone at the base of your spine. People often feel it as a deep ache near the bottom or rectum, which is why they end up seeing a colorectal surgeon rather than a physio. It's typically worse after sitting for a while and when you stand up. Treatment is mainly conservative: a coccyx cushion, anti-inflammatory medication, physiotherapy, and in resistant cases, a nerve block.

Serious Causes — Anal Cancer and Crohn's Perianal Disease

Anal Cancer

Anal cancer is rare. Most cases are squamous cell carcinomas (skin-type cancers) strongly linked to HPV (the human papillomavirus). In its early stages, it's often painless — it may appear as a lump or skin change at the anal margin that could easily be mistaken for a skin tag or haemorrhoid. Pain comes later as the cancer grows, and it tends to be persistent and not clearly linked to bowel motions. A firm, hard, irregular, or ulcerated lump near the anus that doesn't have an obvious explanation should always be assessed by a specialist.

Anal cancer is treated mainly with combined chemotherapy and radiotherapy (not surgery), and outcomes are much better when it's caught early.

Crohn's Perianal Disease

If you have Crohn's disease, around 25–35% of people develop perianal complications. These can include fissures in unusual positions, complex tunnels (fistulae), and abscesses. Perianal Crohn's is particularly painful and needs a coordinated approach from both your gastroenterologist and a colorectal surgeon.

When to Seek Assessment

Please see your GP or ask for a referral to a specialist if you have:

• Anal pain that's been going on for more than 2–3 weeks
• Pain that doesn't have an obvious link to constipation or hard stools
• A lump near the anus, especially if it's tender, warm, or growing
• Fever with perianal pain
• Pain waking you from sleep (beyond the brief spasms of proctalgia fugax)
• Pain that has changed character — particularly if it's become constant
• Any anal pain if you have diabetes, HIV, or are on immune-suppressing medications

Frequently Asked Questions