Anal fissures are longitudinal or elliptical tears of the squamous lining of the distal anal canal.


If present for less than 6 weeks they are defined as acute, and chronic if present for more than 6 weeks. Around 90% of anal fissures occur on the posterior midline.


  • Incidence: 110.00 cases per 100,000 person-years
  • Peak incidence: 30-40 years
  • Sex ratio: more common in females 1:1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+


Risk factors
  • constipation
  • inflammatory bowel disease
  • sexually transmitted infections e.g. HIV, syphilis, herpes

Clinical features


  • the buttocks should be parted to view the anus
  • a digital rectal examination is not recommended as this may cause considerable pain. If the symptoms continue, or there is doubt about the diagnosis then consideration should be given to examination under anaesthesia


Management of an acute anal fissure (< 6 weeks)
  • dietary advice: high-fibre diet with high fluid intake
  • bulk-forming laxatives are first-line - if not tolerated then lactulose should be tried
  • lubricants such as petroleum jelly may be tried before defecation
  • topical anaesthetics
  • analgesia
  • topical steroids do not provide significant relief

Management of a chronic anal fissure (> 6 weeks)
  • the above techniques should be continued
  • topical glyceryl trinitrate (GTN) is first-line treatment for a chronic anal fissure
  • if topical GTN is not effective after 8 weeks then secondary care referral should be considered for surgery or botulinum toxin