Take nitroglycerin tablets under your tongue, not by swallowing them

Nitroglycerin tablets work fastest when placed under your tongue, where the thin tissue absorbs the medication directly into your bloodstream. Do not swallow the tablet or chew it. Sit or lie down as soon as you feel chest pain or the warning signs of an angina attack, then place one tablet under your tongue and let it dissolve. Most people feel relief within 3 to 5 minutes.

The medication comes in small white or reddish tablets, usually in a small glass bottle with a metal cap. Keep the bottle tightly closed and store it in a cool, dry place—not in the bathroom, where humidity breaks down the medication. Check the expiration date on the label; nitroglycerin loses strength over time, especially once the bottle is opened.

Key Takeaways

  • Place the tablet under your tongue and sit or lie down when ready; do not swallow or chew it.
  • Relief usually comes within 3 to 5 minutes; if pain continues after 5 minutes, take a second tablet and call emergency services.
  • Keep the bottle tightly closed and away from heat and moisture, and replace it every 3 to 6 months even if tablets remain.
  • Tell your doctor about all other medications you take, especially erectile dysfunction drugs, because combining them can cause dangerous drops in blood pressure.
  • Carry your nitroglycerin with you at all times during the day, and keep a backup bottle at home or in another location you visit regularly.

What to do when chest pain starts

Stop what you are doing and sit down or lie down flat. Lying down is often better because it reduces the workload on your heart. Remove the nitroglycerin bottle from your pocket or bag and open it carefully—the cap is usually metal and twists off.

Place one tablet under your tongue, directly on the tissue between your lower lip and teeth. Close your mouth and breathe normally. Do not talk or move around. The tablet will begin to dissolve on its own; you may feel a slight tingling or burning sensation under your tongue, which is normal. This sensation means the medication is working.

Set a timer or watch the clock. If the pain has not improved after 5 minutes, place a second tablet under your tongue. If pain continues 5 minutes after the second tablet, or if you have never had chest pain before, call emergency services when ready. Do not drive yourself to the hospital.

Timing and how many tablets to take

Take one tablet at the first sign of chest pain or discomfort. You may take a second tablet after 5 minutes if the first one did not relieve the pain. A third tablet can be taken 5 minutes after the second, but if three tablets over 15 minutes do not stop the pain, call emergency services.

Some people use nitroglycerin before activities they know will trigger chest pain—for example, before climbing stairs or walking in cold weather. Your doctor will tell you if this is right for your situation. If you take it this way, take one tablet 5 to 10 minutes before the activity.

Do not take more than three tablets in a 15-minute period unless your doctor has given you different instructions. If you find yourself needing nitroglycerin more than once or twice a week, tell your doctor at your next visit; this may mean your condition is changing and your treatment plan needs adjustment.

Storage and keeping your medication fresh

Nitroglycerin tablets lose strength quickly once the bottle is opened. Keep the bottle tightly closed at all times, even between doses. Store it in a cool, dry place—a bedroom nightstand or kitchen cabinet works well. Do not store it in the bathroom, car glove compartment, or anywhere hot or humid, because moisture and heat break down the medication.

Replace your nitroglycerin bottle every 3 to 6 months, even if you have not used all the tablets. Write the date you opened the bottle on the label so you know when to replace it. If the tablets have changed color, smell different, or feel damp, throw them away and get a new bottle from your pharmacy.

Keep one bottle with you during the day in a pocket or small bag. Keep a second bottle at home in a place you can reach quickly. If you travel regularly, keep a third bottle in a bag or location you visit often. This way you always have access to the medication when you need it.

Medications and substances that interact with nitroglycerin

Tell your doctor about every medication you take before using nitroglycerin. Do not take nitroglycerin if you use sildenafil (Viagra), tadalafil (Cialis), or other erectile dysfunction medications. Combining these drugs can cause a sudden, dangerous drop in blood pressure that may lead to fainting, stroke, or heart attack.

Alcohol also lowers blood pressure and can cause dizziness or fainting when combined with nitroglycerin. Avoid alcohol, especially right before or after taking a nitroglycerin tablet. If you drink regularly, tell your doctor so they can monitor your blood pressure.

Some blood pressure medications, pain relievers, and decongestants can also interact with nitroglycerin. Your pharmacist can review all your medications and flag any problems. Keep a list of everything you take—prescription, over-the-counter, and supplements—and bring it to every doctor visit.

Side effects and when to call your doctor

Headache is the most common side effect of nitroglycerin and usually goes away after a few doses. Dizziness, lightheadedness, or a feeling of flushing (warmth and redness in the face and neck) are also normal. These effects mean the medication is working. Sit or lie down if you feel dizzy, and the sensation usually passes within a few minutes.

Call your doctor if you have a severe headache that does not go away, persistent dizziness, or fainting. Also call if you develop a rash, swelling of the lips or tongue, or difficulty breathing—these are signs of an allergic reaction and require medical attention. If you have chest pain that does not go away after three nitroglycerin tablets over 15 minutes, call emergency services instead of waiting to reach your doctor.

Frequently Asked Questions

What if I swallow the tablet by mistake?

The tablet will still work, but it will take longer—usually 20 to 30 minutes instead of 3 to 5 minutes. For chest pain, you need fast relief, so place the next tablet under your tongue as directed. If you regularly swallow your tablets by mistake, ask your doctor or pharmacist to show you the correct technique at your next visit.

Can I take nitroglycerin with food or water?

You do not need water or food to take nitroglycerin tablets. Place the tablet under your tongue and let it dissolve on its own. Do not drink water or eat while the tablet is dissolving, because this can wash away the medication before it is fully absorbed.

How do I know if my nitroglycerin tablets are still good?

Fresh nitroglycerin tablets are usually white or reddish and have a slight smell. If the tablets have turned brown, smell like vinegar, feel damp, or crumble easily, they have lost strength and should be replaced. Always replace your bottle every 3 to 6 months, regardless of how many tablets you have used.

What should I do if I take a nitroglycerin tablet but do not have chest pain?

If you took the tablet by mistake, there is no need to panic. You may feel a headache or dizziness, but these side effects are temporary and not dangerous. Sit down and rest until the feeling passes. Do not take another tablet. If you have questions about when to take your medication, ask your doctor or pharmacist.

Can I use an old bottle of nitroglycerin from years ago?

No. Nitroglycerin loses strength over time and may not work when you need it. Always use a fresh bottle from your pharmacy. If you find an old bottle, ask your pharmacist how to dispose of it safely rather than throwing it in the trash.