Fast-Acting Nitroglycerin

Nitroglycerin eases chest pain (angina) by getting more blood and oxygen to your heart. Fast-acting nitroglycerin can stop an angina attack. Follow the steps below for taking this medicine. Note: Your healthcare provider may give you slightly different instructions. If so, follow them carefully.

To stop an angina attack

Closeup of mouth showing fingers placing pill under tongue.Sit down before you take your nitroglycerin. The medicine may make you feel dizzy because it lowers your blood pressure rapidly.

If you use tablets

  • Place 1 tablet under your tongue. Or place it between your lip and gum. Or put it between your cheek and gum.

  • Let the tablet dissolve all the way. Do not swallow or chew the tablet.

  • Do not eat, drink, smoke, or chew tobacco as the tablet is dissolving.

If you use spray

  • 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. Do not 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. Then continue your normal routine.

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. Do not take more than 3 tablets, or spray more than 3 times, within 15 minutes. Stay on the phone with 911 for further instructions.


  • Limit how much 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. 

  • NOTE: Don't take phosphodiesterase inhibitors such as sildenafil. These are medicines that help sexual function 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.

  • Tell your healthcare provider if your angina attacks last longer, occur more often, or are more severe.