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Using Nitroglycerin for Angina


Nitroglycerin is a vasodilator. This is a medicine that widens (dilates) blood vessels. It can relieve angina quickly. That's because it can widen the coronary arteries, which bring blood and oxygen to the heart. This improves blood flow to the heart muscle, which relieves symptoms.

Quick-acting forms of nitroglycerin are used to relieve angina or are used just before activities that typically cause angina.

You may also take daily long-acting medicine to prevent angina. These medicines include nitrates (including nitroglycerin), beta-blockers, and calcium channel blockers. These types of medicines can prevent angina that occurs during daily activities. They are not used to stop sudden symptoms of angina.

How to use quick-acting nitroglycerin

Your doctor will tell you when to use your nitroglycerin. You may need to take it to relieve symptoms or to prevent symptoms from happening.

Be sure to keep nitroglycerin with you at all times.

  • To prevent angina, take nitroglycerin before an activity that causes angina.

    If you know that some activities cause angina, try taking nitroglycerin before you do the activity. An example is walking uphill or having sex.

  • To relieve angina, take one dose of nitroglycerin as soon as you feel symptoms.

    If your symptoms get worse or are not getting better within 5 minutes, call 9-1-1 right away. Stay on the phone. The emergency operator will give you further instructions.

  • Sit or lie down to take your nitroglycerin.

    Taking nitroglycerin can lower your blood pressure, which could cause you to pass out if you are standing up. If you are driving, pull over and park the car.

  • Take your nitroglycerin properly.

    Nitroglycerin comes in different forms. Examples are tablets or an oral spray. Be sure to follow the instructions for your nitroglycerin. Instruction examples include:

    • For under-the-tongue (sublingual) tablets, place the tablet under your tongue. Leave it there until it dissolves. If you accidentally swallow the tablet, take another. The medicine won't work if you swallow it.
    • For between-cheek-and-gum (buccal) tablets, place the tablet between your cheek and gum. Leave it there until it dissolves. If you accidentally swallow the tablet, take another. The medicine won't work if you swallow it.
    • For the oral spray, spray it under your tongue or on top of your tongue. Push the spray canister button and close your mouth right away.
  • Store nitroglycerin correctly.

    Store nitroglycerin pills in a dark-coloured (such as brown), airtight, glass container that you can't see through. Keep the container tightly closed. Keep nitroglycerin pills and liquid spray away from heat or moisture. Do not open your sublingual nitroglycerin until you need a dose.

  • Replace your nitroglycerin if it is past the expiration date.

    Nitroglycerin can get old. And when it is old, it may not work. If your nitroglycerin supply is past its expiration date, get a new prescription as soon as you can.

  • Understand nitroglycerin side effects.

    You may get a headache when you use nitroglycerin. Or you may feel burning or tingling under your tongue with nitroglycerin that is used under the tongue.

Do not take an erection-enhancing medicine. These medicines include sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra). Combining nitroglycerin with any of these medicines can cause a life-threatening drop in blood pressure. If you have angina and have taken one of these medicines, be sure to tell your doctor so that you are not given nitroglycerin or another nitrate medicine.


Current as of: September 7, 2022

Author: Healthwise Staff
Medical Review:
Rakesh K. Pai MD, FACC - Cardiology, Electrophysiology
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology