Diltiazem is a calcium channel blocker that dilates the blood vessels and increases blood flow to the anal fissure, promoting healing. This therapy also reduces pressure in the anal sphincter, which eases the spasms and decreases pain. The dosage is usually a small, pea-sized dot of ointment applied around the anal opening two to three times daily, as well as before and after bowel movements. This treatment has few side effects and is effective when used regularly. Headaches may occur initially for some patients but tend to go away with repeated use.

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“Topical diltiazem ointment in the treatment of chronic anal fissure.” – PubMed

In this study, 59 out of 67 patients treated with diltiazem 2% ointment healed from their anal fissures.