Some commonly used brand names are:

In the U.S.—

In Canada—

Another commonly used name for nitroglycerin is glyceryl trinitrate.

• Antianginal
• Vasodilator, congestive heart failure

Nitrates ( NYE-trates) are used to treat the symptoms of angina (chest pain). Depending on the type of dosage form and how it is taken, nitrates are used to treat angina in three ways:

• to relieve an attack that is occurring by using the medicine when the attack begins;
• to prevent attacks from occurring by using the medicine just before an attack is expected to occur; or
• to reduce the number of attacks that occur by using the medicine regularly on a long-term basis.

When applied to the skin, nitrates are used to reduce the number of angina attacks that occur. The only nitrate available for this purpose is topical nitroglycerin (nye-troe-GLI-ser-in) .

Topical nitroglycerin is absorbed through the skin. It works by relaxing blood vessels and increasing the supply of blood and oxygen to the heart while reducing its work load. This helps prevent future angina attacks from occurring.

Topical nitroglycerin may also be used for other conditions as determined by your doctor.

Nitroglycerin as discussed here is available only with your doctor's prescription, in the following dosage forms:

Topical
• Ointment (U.S. and Canada)
• Transdermal (stick-on) patch (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For nitroglycerin applied to the skin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to nitrates or nitrites. Also tell your health care professional if you are allergic to any other substances, such as certain foods, preservatives, or dyes.

Pregnancy—Nitrates have not been studied in pregnant women. Before taking these medicines, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether this medicine passes into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking these medicines and who wish to breast-feed should discuss this with their doctor.

Children—Studies on these medicines have been done only in adult patients, and there is no specific information comparing use of nitrates in children with use in other age groups.

Older adults—Dizziness or lightheadedness may be more likely to occur in the elderly, who may be more sensitive to the effects of nitrates.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are using nitroglycerin, it is especially important that your health care professional know if you are taking any of the following:

• Antihypertensives (high blood pressure medicine) or
• Other heart medicine or
• Sildenafil—May increase the effects of nitroglycerin on blood pressure

• Anemia (severe)

• Glaucoma—May be worsened by nitroglycerin

• Head injury (recent) or
• Stroke (recent)—Nitroglycerin may increase pressure in the brain, which can make problems worse

• Heart attack (recent)—Nitroglycerin may lower blood pressure, which can aggravate problems associated with heart attack

• Kidney disease or
• Liver disease—Effects may be increased because of slower removal of nitroglycerin from the body

• Overactive thyroid

Use nitroglycerin exactly as directed by your doctor. It will work only if applied correctly.

The ointment and transdermal forms of nitroglycerin are used to reduce the number of angina attacks. They will not relieve an attack that has already started because they work too slowly. Check with your doctor if you need a fast-acting medicine to relieve the pain of an angina attack.

This medicine usually comes with patient instructions. Read them carefully before using this medicine.

For patients using the ointment form of this medicine:

• Before applying a new dose of ointment, remove any ointment remaining on the skin from a previous dose. This will allow the fresh ointment to release the nitroglycerin properly.
• This medicine comes with dose-measuring papers. Use them to measure the length of ointment squeezed from the tube and to apply the ointment to the skin. Do not rub or massage the ointment into the skin; just spread in a thin, even layer, covering an area of the same size each time it is applied.
• Apply the ointment to skin that has little or no hair.
• Apply each dose of ointment to a different area of skin to prevent irritation or other skin problems.
• If your doctor has ordered an occlusive dressing (airtight covering, such as kitchen plastic wrap) to be applied over this medicine, make sure you know how to apply it. Since occlusive dressings increase the amount of medicine absorbed through the skin and the possibility of side effects, use them only as directed. If you have any questions about this, check with your health care professional.

For patients using the transdermal (stick-on patch) system:

• Do not try to trim or cut the adhesive patch to adjust the dosage. Check with your doctor if you think the medicine is not working as it should.
• Apply the patch to a clean, dry skin area with little or no hair and free of scars, cuts, or irritation. Remove the previous patch before applying a new one.
• Apply a new patch if the first one becomes loose or falls off.
• Apply each dose to a different area of skin to prevent skin irritation or other problems.

Dosing—

The dose of nitroglycerin will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of nitrates. If your dose is different, do not change it unless your doctor tells you to do so.

For nitroglycerin
• For angina (chest pain):
  • For ointment dosage form:
    • Adults—15 to 30 milligrams (mg) (about one to two inches of ointment squeezed from tube) every six to eight hours.
    • Children—Use and dose must be determined by your doctor.
  • For transdermal system (skin patch) dosage form:
    • Adults—Apply one transdermal dosage system (skin patch) to intact skin once a day. The patch is usually left on for 12 to 14 hours a day and then taken off. Follow your doctor's instructions for when to put on and take off the skin patch.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

• For patients using the ointment form of this medicine: If you miss a dose of this medicine, apply it as soon as possible unless the next scheduled dose is within 2 hours. Then go back to your regular dosing schedule. Do not increase the amount used.
• For patients using the transdermal (stick-on patch) system: If you miss a dose of this medicine, apply it as soon as possible. Then go back to your regular dosing schedule.

Storage—

• To store the ointment form of this medicine:
  • Keep out of the reach of children.
  • Store the tube of nitroglycerin ointment in a cool place and keep it tightly closed.
  • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.
• To store the transdermal (stick-on patch) system :
  • Keep out of the reach of children.
  • Store away from heat and direct light.
  • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
  • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Do not take sildenafil (e.g., Viagra) if you are taking this medicine. When sildenafil is taken with nitrates, the combination can lower blood pressure and cause dizziness, lightheadedness, or fainting. In some case, sildenafil taken with nitrates has caused death.

If you have been using nitroglycerin regularly for several weeks or more, do not suddenly stop using it. Stopping suddenly may bring on attacks of angina. Check with your doctor for the best way to reduce gradually the amount you are using before stopping completely.

Dizziness, lightheadedness, or faintness may occur , especially when you get up quickly from a lying or sitting position. Getting up slowly may help. If you feel dizzy, sit or lie down.

The dizziness, lightheadedness, or fainting is also more likely to occur if you drink alcohol, stand for long periods of time, exercise, or if the weather is hot. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for long periods of time.

After using a dose of this medicine you may get a headache that lasts for a short time. This is a common side effect, which should become less noticeable after you have used the medicine for a while. If this effect continues, or if the headaches are severe, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Rare
  • Blurred vision;  dryness of mouth;  headache (severe or prolonged) 
  
  

• Signs and symptoms of overdose (in the order in which they may occur)
  • Bluish-colored lips, fingernails, or palms of hands;  dizziness (extreme) or fainting;  feeling of extreme pressure in head;  shortness of breath ;  unusual tiredness or weakness;  weak and fast heartbeat;  fever;  convulsions (seizures) 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Dizziness or lightheadedness, especially when getting up from a lying or sitting position;  fast pulse;  flushing of face and neck;  headache ;  nausea or vomiting;  restlessness  
  
  

• Less common
  • Sore, reddened skin 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in the product labeling, topical nitroglycerin is used in certain patients with the following medical conditions:

• Chronic anal fissures

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for this use.