Nitroglycerin transdermal (skin patch) is used to prevent attacks of chest pain (angina). nitroglycerin will not treat an angina attack that has already begun.

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

You should not use nitroglycerin if you are allergic to any type of adhesive on a bandage or other transdermal skin patch, or if you are using medicine to treat pulmonary arterial hypertension, such as riociguat.

Do not take erectile dysfunction medicine (Viagra, Cialis, and others) while you are using nitroglycerin transdermal, or you could have a sudden and serious decrease in blood pressure.

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

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

Wash your hands after applying or removing a skin patch.

Do not wear more than one nitroglycerin transdermal patch at a time. Using extra skin patches will not make the medication more effective. Never cut a skin patch.

The nitroglycerin skin patch is usually worn for 12 to 14 hours and then removed. A new patch is put on after a "patch-free" period of 10 to 12 hours. Your doctor may want you to wear the patch for longer or shorter periods of time. Follow your doctor's instructions carefully.

You may have very low blood pressure while using nitroglycerin. Call your doctor if you are sick with vomiting or diarrhea, or if you are sweating more than usual.

Nitroglycerin transdermal will not work fast enough to treat an angina attack. Your doctor may prescribe a fast-acting medicine to treat an angina attack. Tell your doctor if it seems like any of your medicines don't work as well in treating or preventing angina attacks.

If you need surgery or medical tests, tell the surgeon or doctor ahead of time that you are using nitroglycerin transdermal.

Do not stop using this medicine without your doctor's advice, even if you feel fine. You may have increased angina attacks if you stop using the medication suddenly.

Store at room temperature, away from moisture and heat. Do not refrigerate. Keep each skin patch in its sealed pouch until you are ready to use it.

After removing a skin patch fold it in half, sticky side in, and throw it away in a place where children or pets cannot get to it. Keep both used and unused nitroglycerin skin patches out of the reach of children or pets.

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

• allergy to any type of adhesive on a bandage or other transdermal skin patch; or

• you are using medicine to treat pulmonary arterial hypertension, such as riociguat.

Do not take erectile dysfunction medicine (Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil, vardenafil) while you are using nitroglycerin transdermal. Using erectile dysfunction medicine with nitroglycerin can cause a sudden and serious decrease in blood pressure.

Tell your doctor if you have ever had:

• a heart attack or other heart problems;

• a stroke or head injury; or

• low blood pressure.

Tell your doctor if you are pregnant or breastfeeding.

Apply a patch as soon as you remember, and keep it on for the rest of your wearing time without changing your patch removal schedule. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra patches to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. The amount of nitroglycerin in a used skin patch could be dangerous to a child or pet who accidentally chews on the patch.

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.

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:

• worsening chest pain;

• 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.

Serious side effects may be more likely in older adults.

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

Common side effects of nitroglycerin may include:

• headache; or

• feeling light-headed.

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, heparin;

• medicine used to treat blood clots;

• blood pressure medication; or

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

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.