Good pain killer for a anal fissure?

Before treatment...: Could you be referring to fissures, fistula, abscess? Sexually transmitted disease (syphilis, gc, hiv, etc.) should be considered. Hemorrhoids & rectal prolapse can appear as a painful swelling. Anal trauma of any kind may cause mechanical injury. Skin eruptions need to be considered. But if fissure is confirmed, topical Nitroglycerin is traditionally used, although other agents can be compounded.