Nitroglycerin rectal is used to treat moderate to severe pain caused by chronic anal fissures (tears in the skin lining your rectum).

Nitroglycerin rectal may also be used for purposes not listed in this medication guide.

You should not use this medicine if you are also using medicine to treat pulmonary arterial hypertension or erectile dysfunction, or if you have severe anemia (a lack of red blood cells), or increased pressure inside your skull.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Do not take a rectal suppository or enema by mouth. Use it only in your rectum.

Nitroglycerin rectal can cause severe headaches. Ask your doctor before using any headache pain medication.

It may take up to 3 weeks before your symptoms improve. Keep using as directed and tell your doctor if your symptoms do not improve or if they get worse while using nitroglycerin rectal.

Store at room temperature away from moisture and heat. Keep the tube tightly closed when not in use. Throw away any nitroglycerin rectal ointment you have not used within 8 weeks after you first opened the tube.

You should not use nitroglycerin rectal if you are allergic to it, or if you have:

• severe anemia (a lack of red blood cells);

• increased pressure inside the skull; or

• if you also use erectile dysfunction medicine such as Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil, or vardenafil.

Do not use nitroglycerin rectal if you have early signs of a heart attack (chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling). Seek emergency medical attention if you have symptoms of a heart attack.

Tell your doctor if you have ever had:

• congestive heart failure;

• heart attack;

• a blood vessel disorder;

• low blood pressure; or

• headaches.

Tell your doctor if you are pregnant or breastfeeding.

Nitroglycerin rectal is not approved for use by anyone younger than 18 years old.

Use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of nitroglycerin can be fatal.

Overdose symptoms may include a severe throbbing headache, confusion, fever, fast or pounding heartbeats, dizziness, vision problems, vomiting, bloody diarrhea, trouble breathing, cold or clammy skin, fainting, and seizures.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Drinking alcohol can increase certain side effects such as dizziness, drowsiness, feeling light-headed, or fainting.

Avoid getting nitroglycerin in your eyes, mouth, or vagina.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Nitroglycerin may cause serious side effects. Call your doctor at once if you have:

• pounding heartbeats or fluttering in your chest;

• slow heart rate;

• a light-headed feeling, like you might pass out; or

• heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating.

Nitroglycerin can cause severe headaches. These headaches may gradually become less severe as you continue to use nitroglycerin. Do not stop using nitroglycerin. Ask your doctor before using any headache pain medication.

Common side effects of nitroglycerin may include:

• headache; or

• dizziness.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all your current medicines, especially:

• aspirin or heparin;

• medicine used to treat blood clots;

• blood pressure medication;

• ergot medicine--dihydroergotamine, ergotamine, ergonovine, methylergonovine.

• other nitroglycerin medication.

This list is not complete and many other drugs may affect nitroglycerin. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.