An anal fissure is a crack-like sore in the anal region. It is the commonest reason for pain in this area. Causes include constipation and the passage of hard stools. As well as being painful, anal fissures may bleed moderately. They can be a particular problem for cyclists and horse riders. The best treatment is scrupulous hygiene, avoidance of constipation by eating a high-fibre diet, and drinking plenty of water. Sometimes analgesic anti-inflammatories are prescribed.

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