Take the tablet under your tongue and let it dissolve

When you feel chest pain or pressure, place one nitroglycerin tablet under your tongue and close your mouth. Do not swallow it whole. The tablet will dissolve on its own in one to three minutes. The medicine absorbs directly through the tissue under your tongue and enters your bloodstream quickly — much faster than if you swallowed it.

Sit or lie down before taking the tablet. Nitroglycerin lowers blood pressure, and you may feel lightheaded or dizzy as it works. Sitting down keeps you safe if that happens. Stay seated or lying down for at least five to ten minutes after taking the dose.

You should feel relief from chest pain within five minutes. If the pain does not improve after five minutes, take a second tablet the same way. If pain persists after a third tablet taken five minutes apart, call 911 when ready — do not drive yourself to the hospital.

Key Takeaways

  • Place the tablet under your tongue and let it dissolve; do not swallow it.
  • Sit or lie down before taking the tablet to prevent dizziness or fainting.
  • Relief usually comes within five minutes; if it does not, take a second dose five minutes later.
  • Call 911 if three tablets taken five minutes apart do not stop the chest pain.
  • Keep your tablets in a cool, dark place and check the expiration date regularly, as nitroglycerin loses strength over time.

Prepare before you need it

Keep your nitroglycerin tablets with you at all times, especially if you have a history of chest pain or angina. Store them in their original brown or amber glass bottle — the dark glass protects the tablets from light, which breaks down the medicine. Keep the bottle tightly closed and store it at room temperature, away from heat and moisture.

Check the expiration date on your bottle every month. Nitroglycerin tablets lose potency quickly once the bottle is opened, even if they have not reached the printed expiration date. Most doctors recommend replacing your bottle every three to six months, even if you have not used all the tablets. If your tablets have lost their sharp, biting taste or smell, they have degraded and should be replaced.

Tell your family members, coworkers, or anyone you spend time with regularly where you keep your tablets. If you collapse, they need to know where to find them and how to help you take one.

What to expect as the tablet works

As the nitroglycerin dissolves, you may feel a slight burning or tingling under your tongue — this is normal and means the tablet is working. Your heart rate may increase slightly. You might feel a warm flush in your face or neck, or a mild headache. These side effects usually fade within a few minutes and are not dangerous.

Some people feel dizzy or lightheaded as their blood pressure drops. This is why sitting down matters. If you feel faint, lie down flat with your legs raised slightly. The dizziness should pass within a few minutes. If it does not, or if you feel chest pain spreading to your arm, jaw, or back, call 911.

When to take a second or third dose

If your chest pain has not improved five minutes after taking the first tablet, take a second one the same way — under your tongue, sitting or lying down. Wait another five minutes. If pain is still present, take a third tablet.

If you have taken three tablets, each five minutes apart, and the pain has not stopped or has gotten worse, call 911 when ready. Do not take a fourth tablet or wait any longer. Chest pain that does not respond to nitroglycerin can signal a heart attack, and you need emergency care.

Nitroglycerin and other medications

Tell your doctor about all medications and supplements you take before using nitroglycerin. Some drugs interact dangerously with it. Most importantly, never take nitroglycerin if you have taken a medication for erectile dysfunction — such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra) — within the past 24 to 48 hours. The combination can cause a severe, life-threatening drop in blood pressure.

Certain blood pressure medications, heart medications, and some pain relievers can also interact with nitroglycerin. Your pharmacist can review your full medication list and flag any conflicts. If you start a new medication, ask whether it is safe to use with nitroglycerin before you take it.

Long-term nitroglycerin use and tolerance

If you take nitroglycerin regularly — not just during chest pain episodes — your body can build tolerance to it over time. This means the tablets become less effective. Your doctor may recommend a "nitrate-free window," a period of 10 to 12 hours each day when you do not take nitroglycerin, to help prevent tolerance from developing.

If you notice that your tablets are not working as well as they used to, or if you need to take them more often, tell your doctor. Do not increase the dose on your own. Your doctor may adjust your treatment plan or switch you to a different medication.

Frequently Asked Questions

Can I take nitroglycerin if I am not sure it is a heart problem?

Yes. If you have chest pain or pressure and your doctor has prescribed nitroglycerin, take it as directed. Nitroglycerin is safe to use even if the pain turns out not to be heart-related. However, if you take it and the pain does not improve, or if you are unsure whether the pain is serious, call 911 or seek emergency care.

What if I swallow the tablet by accident?

It will still work, but much more slowly — it may take 20 to 30 minutes instead of five. If you swallow it by accident, sit down and wait. If your pain does not improve within 10 minutes, take another tablet under your tongue the correct way. Do not take extra doses to make up for the one you swallowed.

Can I drink alcohol while taking nitroglycerin?

Alcohol can increase the dizziness and lightheadedness that nitroglycerin causes. If you drink, do so in moderation and be aware that the combination may make you feel faint. Avoid alcohol entirely if you are taking long-acting nitroglycerin medications.

How should I dispose of old or expired nitroglycerin tablets?

Do not flush them down the toilet or throw them in the trash. Take them to a pharmacy — most pharmacies have a medication disposal program and will take old nitroglycerin tablets for free. Some communities also have hazardous waste collection days where you can drop off medications.

What if I lose my nitroglycerin bottle?

Contact your doctor or pharmacist right away and ask for a replacement. Do not wait until you have chest pain to replace it. Your doctor can write a new prescription, and your pharmacy can fill it the same day in most cases. Keep a backup bottle at home or at work if possible.