In short
A small tear in the skin of the anal canal causes pain out of all proportion to its size. Most heal with softer stools and warm baths, and healing depends on breaking the cycle of pain and spasm.
Emergency if: Heavy rectal bleeding, black tarry stools, fever with severe anal pain and swelling suggesting an abscess, or feeling faint with blood loss.
On your report
Hemoglobin, Ferritin, CRP, ESR +1 more
On this page
01
What it feels like
An anal fissure is a small tear in the lining of the anal canal, and it produces a characteristic set of symptoms: severe, sharp pain when passing a stool, a burning pain afterwards that may last for several hours, and bright red blood in the toilet or on the paper.
That combination distinguishes it from haemorrhoids, which more often cause painless bleeding, itching or a lump. The pain of a fissure is disproportionate to its size and is the reason people delay going to the toilet, which quietly makes the problem worse.
02
Why it keeps hurting
The tear triggers spasm in the muscular ring around the anus. That spasm both causes much of the pain and reduces blood flow to the area, and because good blood supply is what heals a wound, the spasm actively prevents the tear closing. This self-sustaining loop is why a fissure that should heal in days can persist for months.
Every effective treatment interrupts the loop somewhere: softening stools stops repeated tearing, warm baths relax the muscle, and the prescribed creams work by relaxing the muscle and improving blood flow. Understanding the loop makes the treatment plan make sense.
03
What causes it
Constipation and straining to pass hard stools are the most common triggers, but repeated diarrhoea can also do it. Pregnancy and vaginal childbirth are frequent causes. Fissures are most common in people aged 15 to 40 and in young children, where they are a leading reason for blood on the nappy.
Some fissures point to an underlying condition rather than simple trauma. Inflammatory bowel disease including Crohn's disease and ulcerative colitis, and certain sexually transmitted infections, can cause them. A fissure that is off to the side rather than front or back, that is unusually large, or that is not healing is investigated rather than simply re-treated.
04
Self-care that works
The core measure is making stools soft and easy to pass: plenty of fluids, fibre-rich foods increased gradually, and a laxative if needed, aiming for stools that are soft and formed rather than loose. Warm shallow baths after passing a stool relax the muscle and provide real relief, and simple painkillers such as paracetamol or ibuprofen help.
Go as soon as you feel the urge rather than putting it off, since holding on hardens the stool and worsens the tear. Avoid straining and prolonged sitting on the toilet, and keep the area clean and dry, using water and gentle patting instead of vigorous wiping. Avoid scented wipes and soaps, which irritate.
05
Medical treatment and when to seek it
If self-care is not enough, a doctor may prescribe laxatives, stronger pain relief, and a cream applied to the anus that helps with healing by relaxing the muscle and improving blood flow — this may need to be used for up to 8 weeks. Headache is a common side effect of these creams and usually settles over the first few days.
See a doctor if symptoms have not improved after about 7 days of self-treatment. For fissures that persist despite creams, options include an injection to relax the muscle or a small surgical procedure under general anaesthetic, which is highly effective but is kept for resistant cases because it carries a small risk of affecting continence.
06
Do not assume it is a fissure
Bright red rectal bleeding is common and usually benign, but it should not be self-diagnosed indefinitely. Get it assessed if bleeding continues beyond a couple of weeks, if it is mixed into the stool rather than on the surface, or if it comes with a change in bowel habit, weight loss, or a family history of bowel cancer.
Age lowers the threshold considerably: new rectal bleeding in an adult over 40 deserves assessment even when a fissure seems the obvious explanation. Dark or black tarry stools are a different matter entirely, indicating bleeding higher up the digestive tract, and need urgent attention.
When to act
Routine — see a doctor
Sharp pain on passing a stool with a little bright red blood: soften stools, warm baths and pain relief, reviewing if not improving after about a week.
Same-day — call promptly
Bleeding that continues beyond a couple of weeks, blood mixed into the stool, a change in bowel habit, weight loss, or new bleeding over age 40.
Emergency — act now
Heavy rectal bleeding, black tarry stools, fever with severe anal pain and swelling suggesting an abscess, or feeling faint with blood loss.
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Sources
- Anal Fissure — NHSnhs.uk
- Anal Disorders — MedlinePlusmedlineplus.gov
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