What role do topical treatments, such as glyceryl trinitrate or diltiazem, play in the management of anal fissures?

Topical treatments such as glyceryl trinitrate (GTN) and diltiazem play a key role in the management of anal fissures by promoting healing through relaxation of the internal anal sphincter and improving blood flow.

GTN ointment acts as a nitric oxide donor, relaxing the internal anal sphincter, reducing anal pressure, and enhancing blood flow, which aids fissure healing. It is recommended to consider prescribing rectal GTN 0.4% ointment if symptoms persist for more than one week without improvement, applying twice daily for 6–8 weeks to allow re-epithelization and reduce relapse risk. However, about 25% of patients experience headaches as a side effect, which may affect compliance. Increasing the dose does not improve healing but increases side effects. GTN ointment should be avoided in children, pregnancy, and breastfeeding ¹.

Diltiazem, a calcium-channel blocker and vasodilator, similarly increases blood flow and relaxes muscle tone. Evidence suggests topical diltiazem and rectal GTN ointment are equally effective in managing anal fissures, but diltiazem is associated with fewer headaches and lower recurrence rates. It is considered when patients cannot tolerate GTN due to adverse effects. Both treatments are primarily used for acute fissures and have limited benefit in chronic fissures with scarring, where secondary care options may be needed ¹.