Pearls: Nitroglycerin Ointment for Anal Fissure

Many times patients come in with complaints of hemorroids, but what they really mean is they are having pain with bowel movements.  The most common cause of anal pain without an external lump is an anal fissure.  Anal fissures are tears in the anoderm, and are almost always posterior midline.  Usually these can be seen without a speculum on examination, just by spreading the buttocks.  Sometimes a sentinel pyle will be present at the outermost extension of the fissure, and indicate the fissure is chronic. The other major cause of anal pain, thrombosed external hemorrhoids, can be readily identified by taking a history from the patient and by examination.  If there is no external lump, most likely pain with defectation is secondary to an anal fissure.

The most common cause of anal fissures and the easiest to treat is passage of hard stools.  Some patients may deny they have constipation even if they have hard stools, so ask specifically about hard stools.  Diarrhea can also cause fissures, and this can be harder to treat.

Most fissures are posterior midline fissures, although some women will have anterior fissures.  Fissures in atypical locations can indicate inflammatory bowel disease.  If a patient has an anal fissure, an anoscopic examination will be very painful, and most fissures can be seen without inserting anything into the anal canal.

Most fissures can be healed with conservative treatment.  Treating fissures requires a two prong attack:  Softening the stools and treating anal sphincter spasm.  Anal spasm is triggered by pain, and may cause a relative ischemia to the anoderm in the posterior midline, impairing healing.

While pain is the most common symptom of fissure, bleeding can also occur.   The treating physician should make sure any rectal bleeding is not from a more serious cause, especially in older patients.



To treat the hard stools, increase dietary fiber, use fiber bulking agents (psyllium powder) and increase fluid intake.

To treat the anal spasm, and the pain, have the patient take Sitz baths (warm water, no additives, 10 minute duration) three times a day if possible, and after a bowel movement.

To further treat anal sphasm, an ointment of 0.2% to 0.4% nitroglycerin  ointment can be be applied to the perianal area, not in the anal canal, two to three times a day.   Around 5% of patients will get headaches to the nitroglycerin but will develop tachyphylaxis to this.  Tylenol is used for these headaches.  To minimize headaches, for the first 3-5 days of treatment, apply the nitroglycerin ointment once daily right before going to bed.  Being supine may minimize the nitroglycerin headaches.  Tell the patients to use a glove to apply the ointment or wash their hands immediately after application, as the ointment can be absorbed through the finger.  Only a small amount of ointment is applied.  After this initial period, if everything is going well, increase the application frequency to twice daily.

The nitroglycerin ointment can be compounded with 1% lidocaine ointment by the pharmacist.  There are no commercial products of nitroglycerin available in this strength, so compounding by the pharmacist is necessary.

The pain will resolve before the fissure is entirely healed, so have the patient continue the therapy beyond the period when symptomatic relief first occurs.   Over time, have the patient wean the Sitz baths and nitroglycerin therapy, but continue a stool softening regimen for life.

Conservative therapy should heal approximately 70% or more of anal fissures.  Surgerical referral can be made if symptoms do not resolve with aggressive conservative therapy.

Don't use 2% Nitropaste as a substitute, as this seems to cause localized discomfort when applied, along with increased risk of side effects (headache).