Chronic anal fissure: 0.2% topical glyceryl trinitrate ointment

Summary of possible benefits and harms

A large review of 18 studies, in mostly adults, found that glyceryl trinitrate (used in various strengths) was only slightly better than placebo treatment (one that doesn't contain any active ingredient) at healing chronic anal fissure. This showed that approximately 1 in every 2 people who were using glyceryl trinitrate had a healed fissure compared with approximately 1 in every 3 people who were using placebo (one that doesn't contain any active ingredient). It also found that the anal fissure came back in about half of the people who seemed to be cured with glyceryl trinitrate.

No studies were found that looked at how well the 0.2% strength of the glyceryl trinitrate ointment worked compared with the 0.4% ointment in treating chronic anal fissure in children, young people or adults.

Just 4 small studies were found that looked at how well different strengths of glyceryl trinitrate ointment (0.1%, 0.2% and 0.4%) worked compared with a placebo ointment (one that doesn't contain any active ingredient). Because these studies didn't compare the different strengths with each other, we don't really know which strengths of ointment are better or worse than the others, including the 0.2% and 0.4% strengths of glyceryl trinitrate.

No studies were found that looked at whether using the 0.2% strength of the glyceryl trinitrate ointment caused fewer headaches than using the 0.4% ointment in children or young people under the age of 18 years.

One small study (181 adults) found that using a lower strength of glyceryl trinitrate caused fewer headaches in adults. The study showed that approximately 1 in every 3 adults who were using the 0.2% glyceryl trinitrate ointment for 8 weeks experienced a headache, compared with approximately 2 out of 3 adults who were using the 0.4% ointment. However, it is important to recognise that these results are from only 47 adults who used the 0.2% ointment and only 37 adults who used the 0.4% strength for 8 weeks. Small studies like this are less reliable than larger ones, and any possible benefits from using a lower strength ointment may have been different if more people had taken part.