Health Library

Health Library Explorer
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A-Z Listings

Discharge Instructions: Taking Fast-Acting Nitroglycerin

Your healthcare provider prescribed nitroglycerin for you. This medicine relieves chest pain caused by a lack of blood flow to the heart (angina). It does this by getting more oxygen-rich blood to your heart. It relaxes the blood vessels in the heart as well as the rest of the body. Fast-acting nitroglycerin can stop an angina attack. Follow the steps below for taking fast-acting nitroglycerin. Note: Your healthcare provider may give you slightly different instructions. If so, follow them carefully.

The name of my fast-acting nitroglycerin medicine is ________________________________.

To stop an angina attack 

Sit down before you take your nitroglycerin. The medicine may make you feel dizzy because it lowers blood pressure rapidly.

Using fast-acting tablets

  • Place 1 tablet under your tongue. You can also place it between your lip and gum, or between your cheek and gum.

  • Let the tablet dissolve completely. Don’t swallow or chew the tablet. It can be helpful to have a sip of water beforehand to help it dissolve.

  • As the tablet is dissolving, don't eat or drink anything, or smoke or chew tobacco.

Using fast-acting spray

  • Prime the pump before use.

  • Open your mouth and hold the sprayer just in front of your mouth.

  • Press the button on the top. Spray once on or under your tongue. Don't inhale.

  • Close your mouth. Then wait a few seconds before you swallow.

After taking 1 tablet or spraying once

  • Continue sitting for 5 minutes.

  • If the angina goes away completely, rest for a while and continue your normal routine.

Call 911

Call 911 if your angina lasts longer than 5 minutes and 1 tablet or 1 spray has not relieved it. Don't delay. You may be having a heart attack!

After you call 911, take a second tablet. Or spray a second time. Wait another 5 minutes. If the angina still does not go away, take a third tablet, or spray a third time. Don't take more than 3 tablets, or spray more than 3 times, within 15 minutes. Stay on the phone with 911 for more instructions. 


  • Limit the amount of alcohol you drink. Too much alcohol can cause dizziness or fainting.

  • Tell your healthcare provider about any medicines, supplements, or herbs you use. Nitroglycerin can interact with other medicines. This can cause serious problems.

  • Don't take phosphodiesterase inhibitors, such as sildenafil (Viagra) or tadalafil (Cialis) at any time if you are on nitroglycerin treatment. These are medicines used to treat sexual dysfunction in men. The combination of nitroglycerin with these medicines can cause a severe drop in blood pressure. This can lead to dizziness, fainting, heart attack, or stroke.

  • Check when your medicine expires. Nitroglycerin can become less effective over time.

  • Keep some nitroglycerin with you at all times.

  • Keep nitroglycerin in its original container. Store in a dry place (not the bathroom) at room temperature away from heat and light.

  • Tell your healthcare provider if your angina attacks last longer, occur more often, or are more severe as this can be a sign of coronary artery disease that is getting worse. 

Possible side effects of nitroglycerin

If you have any of these side effects, tell your healthcare provider right away. But don’t stop taking the medicine until your healthcare provider tells you to. Mild side effects include:

  • Headache

  • Dizziness or lightheadedness

  • Mouth tingling or burning

  • Edema

  • Abdominal pain

When to call your healthcare provider

Call your healthcare provider right away if any of the following occur:

  • Signs of an allergic reaction, such as trouble breathing, tightness in the chest or throat, wheezing, rash, hives, swelling of the mouth, face, or throat.

  • Severe headache

  • Severe dizziness, or fainting

  • Nausea or vomiting

  • Fast heartbeat (higher than 100 beats per minute), slow heartbeat, or irregular heartbeat

  • Flushing (redness of the face, neck, or chest)

  • Blurred eyesight

  • Dry mouth

  • Sweating a lot

  • Pale skin

  • Restlessness

  • Swollen ankles

  • Weakness or tiredness

  • Angina attacks that last longer, occur more often, or are more severe than in the past or occur at rest

Online Medical Reviewer: Callie Tayrien RN MSN
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Online Medical Reviewer: Steven Kang MD
Date Last Reviewed: 3/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.