Synopsis
Recognise a typical anal fissure, identify atypical secondary causes, and sequence bowel regulation, topical sphincter relaxation and continence-preserving specialist intervention.
- The classic symptom is sharp tearing pain during defaecation followed by burning or spasm lasting minutes to hours, often with a small amount of bright blood.
- Most primary fissures are posterior midline; an anterior fissure can occur, particularly after childbirth, but lateral or multiple fissures require investigation for secondary disease.
- Chronic fissures show exposed sphincter fibres, a sentinel skin tag or hypertrophied anal papilla and persist despite basic bowel measures.
Key red flags
Lateral, multiple, painless, irregular or broad ulcers raise Crohn disease, HIV-related or sexually transmitted infection, tuberculosis, haematological disease, trauma or anal cancer and warrant specialist assessment.
Investigation priorities
Confirm site, chronic features and competing visible pathology.
Management branches
A concordant painful midline tear without secondary-disease features.
- Explain the pain–spasm–constipation cycle, provide gentle hygiene advice and offer warm shallow bathing and non-constipating analgesia for symptom relief.
- Make stool consistently soft using gradual dietary fibre, adequate fluids and a formulary laxative; address diarrhoea as actively as constipation when it is the trigger.
Key medicines
Macrogol or another suitable laxativeTitrate the locally preferred product until stool is soft and easily passed.
Glyceryl trinitrate rectal ointmentApply the licensed preparation according to current BNF instructions for the full course.