What is the primary risk factor for developing an anal fissure?

Chronic constipation is the primary risk factor for developing an anal fissure because it leads to the passage of hard, dry stools. When individuals experience constipation, they may have to strain significantly during bowel movements. This straining can cause trauma to the anal canal, resulting in the tearing of the delicate anal mucosa, which manifests as an anal fissure.

A diet high in fiber is actually beneficial and can help in softening the stool, which reduces the risk of fissures rather than contributing to their formation. While excessive weight and low hydration can contribute to other gastrointestinal issues, they are not as directly linked to the development of anal fissures as chronic constipation is. Fissures are most commonly seen in individuals who have bowel habits characterized by infrequent stools, leading to difficulty and straining during defecation.