Nitroglycerin cream can provide temporary relief from anal fistula symptoms as it improves blood flow and speed up the healing process. It can be directly applied to the anal canal after dilution to get relief from symptoms of fistula. However, the ointment should be used only after consulting with the doctor. However, it is to be kept in mind that no ointment can provide a permanent cure for anal fistula. If you are diagnosed with the condition, you will need surgery sooner or later to permanently get rid of the condition.