How does this medication work? What will it do for me?

Nitroglycerin belongs to the class of medications called antianginals. Nitroglycerin ointment is used to prevent angina attacks (chest pain). Nitroglycerin reduces the number of angina attacks by relaxing blood vessels and increasing the oxygen and blood supply to the heart. Nitroglycerin ointment is not intended for immediate relief of angina.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each tube of ointment contains 2% nitroglycerin. Nonmedicinal ingredients: lactose, lanolin, petrolatum, and purified water (all USP standard).

How should I use this medication?

Nitroglycerin ointment may be applied every 3 to 8 hours if necessary, but one application at bedtime is often sufficient for the entire night. The usual dose is 2.5 cm to 5 cm as squeezed from the tube onto the applicator.

You may use the ointment on any convenient skin area - many people prefer to apply it to the chest. Place the applicator with the ointment side down onto the desired area. Spread the ointment over at least a 5 cm by 7.5 cm area in a thin, uniform layer. Cover the ointment with the supplied paper, plastic kitchen wrap, or other suitable material. This can be held in place with adhesive or transparent tape.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are applying the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, apply it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not apply a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Nitroglycerin ointment should not be used by anyone who:

  • is allergic or sensitive to nitroglycerin or to any of the ingredients of the medication
  • is allergic or sensitive to any organic nitrates
  • is taking erectile dysfunction medications called PDE-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
  • has extremely low blood pressure
  • has increased eye pressure (glaucoma)
  • has increased pressure within the head (e.g., after an accident)
  • has severe anemia

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • dizziness or lightheadedness, especially when getting up from a lying or sitting position
  • fast heartbeat
  • flushing of the face and neck
  • headache
  • nausea or vomiting
  • restlessness
  • sore, reddened skin

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

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

  • blurred vision
  • dryness of the mouth
  • headache (severe or prolonged)

Contact a doctor at once if any of the following signs of overdose occur:

  • bluish-coloured lips, fingernails, or palms of the hands
  • convulsions (seizures)
  • dizziness (extreme) or fainting
  • feeling of extreme pressure in head
  • fever
  • shortness of breath
  • unusual tiredness or weakness
  • weak and fast heartbeat

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Acute angina attacks: Nitroglycerin ointment is not intended for immediate relief of acute attacks of angina. Sublingual (under the tongue) nitroglycerin preparations (spray or tablets) should be used for this purpose.

Heart attacks: Not enough information exists on the safety of using nitroglycerin ointment during the early phase of a heart attack. If you suspect you are having a heart attack, call 9-1-1.

Low blood pressure: Headaches or symptoms of low blood pressure such as weakness or dizziness, particularly when getting up suddenly from a sitting or lying down position, may result from taking too much nitroglycerin. If these symptoms occur, your doctor may reduce the dose or stop the use of nitroglycerin. People who might be negatively affected by low blood pressure should use nitroglycerin ointment with caution. People who take diuretics or have preexisting low blood pressure may be at more risk of being negatively affected.

Tolerance: People taking nitroglycerin may develop tolerance to the medication, resulting in it not working as well. Tolerance to other nitrates or nitrites can also develop, especially if a medication-free period is not observed each day.

Withdrawal: Dependence may occur with chronic use. To avoid possible withdrawal effects, reduce nitroglycerin ointment use gradually over 4 to 6 weeks.

Pregnancy: This medication has not been studied for use by pregnant women. Be sure to tell your doctor if you are pregnant or planning to become pregnant.

Breast-feeding: It is not known if this medication passes into breast milk. Be sure to discuss with your doctor the risks and benefits of using thi smedication before breast-feeding.

Children: The safety and effectiveness of this medication for children have not been established.

What other drugs could interact with this medication?

There may be an interaction between nitroglycerin ointment and any of the following:

  • alcohol
  • alteplase
  • dihydroergotamine
  • erectile dysfunction medications called PDE-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
  • medications that reduce blood pressure (e.g., vasodilators, calcium channel blockers, ACE inhibitors, beta-blockers, diuretics)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.