Examples

Nitrates may be given in a pill or spray form that is placed under the tongue (sublingual). Skin patches or paste are also available. Nitrates may be injected into a vein in emergency situations, such as during a heart attack.

How to use nitroglycerin pills under the tongue

How It Works

Nitrates open (dilate) the arteries to the heart. This increases blood flow to the heart, relieving chest pain (angina).

Nitrates also dilate veins throughout the body so that they can hold more blood. This reduces the amount of blood going back to the heart, reducing the heart's workload.

Why It Is Used

Nitrates are used to:

• Relieve angina.
• Prevent angina, when used before stressful activities that can cause angina (such as sexual intercourse or walking up stairs or a hill).
• Prevent angina that occurs during daily activities (long-term use).

Spray and sublingual forms of nitroglycerin are available to relieve angina. Longer-acting pill or patch forms may be used for long-term prevention of chest pain during daily activities.

How Well It Works

Nitrates have been shown to improve symptoms, but may only slightly reduce risk of premature death in people having a heart attack.¹

Nitrates reduce strain on the heart and improve blood flow to the heart, which relieves and prevents angina pain.

If the usual dose of nitroglycerin does not relieve chest pain, it often means that the angina may be getting worse or becoming unstable. If this happens, call your doctor immediately.

Side Effects

Side effects of nitrates may include:

• Feeling of pulsating fullness in the head (most common side effect); can also cause headache.
• Drop in blood pressure, which can cause dizziness.
• Burning sensation under the tongue (with sublingual nitroglycerin).

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Different nitrate preparations are often combined. Pills, patches, or paste may be used together with sublingual nitroglycerin to give maximum relief and prevent angina.

Some people develop a tolerance to nitrates if they are used constantly over a long period. Tolerance occurs when a medication loses its effectiveness. A doctor may prescribe a daily schedule of using nitroglycerin 12 to 18 hours on and 6 to 12 hours off to prevent developing this tolerance.

Long-term nitroglycerin medication is often added to other medication (such as beta-blockers or calcium channel blockers) when a person is still having episodes of angina.

Do not take the erection-enhancing medication sildenafil (Viagra), vardenafil (Levitra), or tadalafil (Cialis) if you are taking a nitrate. Combining these two drugs can cause a life-threatening drop in blood pressure. If you develop chest pain and have taken one of these erection-enhancing medications, be sure to tell your health professionals so that they do not attempt to treat you with nitroglycerin or another nitrate medication.

Nitroglycerin may not work well if it is old. If your nitroglycerin supply is past its expiration date, get a new prescription as soon as possible. Usually you should replace your tablets every 3 to 6 months. A nitroglycerin spray may last up to 2 years before it expires.

There are ways to tell whether your nitroglycerin is still working. You should have a headache after you take it. If you use nitroglycerin under your tongue, you should feel a slight tingle or burn when you place or spray it there. If you do not notice these signs, your nitroglycerin is probably old. In this case, contact your health professional and get a new prescription as soon as possible. After you fill your new prescription, throw out your old nitroglycerin.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.

Citations

1. Danchin N, Durand E (2006). Acute myocardial infarction, search date August 2004. Online version of Clinical Evidence (15): 1–24.