Take one tablet when ready, then call 911 right away
If you think you are having a heart attack or severe chest pain, take one nitroglycerin tablet and call 911 at the same time—do not wait to see if the tablet works. Place the tablet under your tongue and let it dissolve. Do not swallow it whole.
The tablet should start working within 5 to 10 minutes. If the chest pain does not improve after 5 minutes, you can take a second tablet. Wait 5 minutes, and if pain persists, take a third tablet. However, do not take more than three tablets total while waiting for the ambulance. The paramedics need to know how many you took and when.
Call 911 before you take anything. Do not drive yourself to the hospital, and do not ask someone to drive you. An ambulance can begin treatment on the way and will take you directly to a hospital equipped to handle heart emergencies.
Key Takeaways
- Take one nitroglycerin tablet under your tongue and call 911 when ready—do not wait to see if it works first.
- If chest pain does not improve after 5 minutes, take a second tablet; after another 5 minutes with no relief, take a third tablet.
- Do not take more than three tablets total, and tell the 911 dispatcher and paramedics exactly how many you took and when.
- Chew an aspirin tablet (if you have one and are not allergic) while waiting for the ambulance, as it can help during a heart attack.
- Never drive yourself or wait at home to see if the pain goes away—paramedics can start treatment in the ambulance.
Why you call 911 first, not after the tablet
Many people take a nitroglycerin tablet and then decide whether to call for help based on whether the pain stops. This delay can be dangerous. Chest pain that feels like pressure, squeezing, or heaviness—especially if it spreads to your arm, jaw, or back—can be a sign of a heart attack, and every minute matters.
Paramedics can start an IV, run an electrocardiogram (EKG), give you oxygen, and monitor your heart rhythm while you are still at home or in the ambulance. They can also alert the hospital so a team is ready when you arrive. If you wait at home, you lose this critical time.
Nitroglycerin works for some types of chest pain but not others. Chest pain from a heart attack may feel better temporarily or may not respond to the tablet at all. The only way to know what is happening is to let medical professionals examine you.
What happens during those 5-minute waits between tablets
After you take the first tablet, sit down or lie back in a comfortable position. Stay calm and breathe slowly. The tablet dissolves under your tongue and enters your bloodstream quickly. You may feel a slight tingling or burning sensation under your tongue, or a mild headache—these are normal.
If the chest pain improves significantly within 5 minutes, you still need to tell the paramedics when they arrive. Do not assume the problem has passed. If pain is still present or only slightly better, take a second tablet at the 5-minute mark. Wait another 5 minutes. If pain persists, take the third tablet.
If you have taken three tablets over 15 minutes and the pain has not improved, stop taking more and focus on staying as calm as possible while waiting for the ambulance. The paramedics will have other medications and treatments available.
Chewing aspirin while you wait
If you have aspirin on hand and are not allergic to it, chew one regular-strength tablet (325 mg) or two to three low-dose tablets (81 mg each) while waiting for the ambulance. Do not swallow it whole—chewing it helps your body absorb it faster. Aspirin can help reduce blood clots during a heart attack.
Do not take aspirin if you are allergic to it, if you are already on a blood thinner prescribed by your doctor, or if you have been told by a doctor not to take it. If you are unsure, skip it and focus on the nitroglycerin and calling 911.
Tell the 911 dispatcher exactly what you took
When you call 911, tell the dispatcher that you are having chest pain and that you have taken nitroglycerin tablets. Be specific: say how many tablets you took, when you took the first one, and whether the pain has improved. This information helps paramedics prepare and decide what treatment to give you when they arrive.
The dispatcher may also ask you questions about the pain—where it is, what it feels like, whether you are short of breath, whether you have a history of heart problems. Answer as clearly as you can. If you are alone and feel faint, tell the dispatcher so they can unlock your door or give you other instructions.
Common mistakes to avoid
Do not swallow nitroglycerin tablets whole. They work much faster under the tongue. Do not chew them unless your doctor has specifically told you to. Do not take more than three tablets in 15 minutes, even if the pain is still there.
Do not wait to see if the pain goes away on its own before calling 911. Do not drive yourself to the hospital. Do not ask a family member to drive you if you can call an ambulance instead. Do not assume that because the pain improved slightly, you do not need medical attention.
Do not take someone else's nitroglycerin tablets. They are prescribed for that person's specific condition and dose. If you do not have your own prescription and are having chest pain, call 911 without the tablet.
What to expect when the paramedics arrive
Paramedics will ask you the same questions the dispatcher did, plus more about your medical history, current medications, and whether you have had chest pain before. They will check your blood pressure, heart rate, and oxygen level. They will likely place stickers on your chest to run an EKG, which shows your heart's electrical activity.
They may start an IV line and give you oxygen. They will transport you to the nearest hospital that can handle heart emergencies, usually a facility with a cardiac catheterization lab. Tell them how many nitroglycerin tablets you took and when, so they know your complete medical picture.
If you have nitroglycerin at home but no prescription
If you have chest pain and nitroglycerin tablets at home but they were not prescribed to you, do not take them. Call 911 instead. Nitroglycerin can lower blood pressure and interact with other medications or conditions you may have. Only take nitroglycerin that was prescribed to you by your doctor.
If you have had chest pain in the past and your doctor prescribed nitroglycerin but you have not filled the prescription, talk to your doctor about getting it filled. Keeping it on hand and knowing how to use it can be important if you have a history of heart problems.
Frequently Asked Questions
What if I take a nitroglycerin tablet and the pain goes away completely?
Call 911 anyway. Chest pain that responds to nitroglycerin can still be a sign of a serious heart condition. You need an EKG and blood tests to determine what caused the pain. Paramedics and hospital doctors can evaluate you and decide whether you need further treatment or monitoring.
Can I take nitroglycerin tablets more than three times?
No. If three tablets over 15 minutes do not relieve the pain, do not take more. Call 911 or make sure you have already called. Taking more tablets will not help and may lower your blood pressure too much. Let paramedics handle it from that point.
What if I feel dizzy or faint after taking nitroglycerin?
Sit down or lie down when ready. Dizziness is a common side effect because nitroglycerin lowers blood pressure. If you are on the phone with 911, tell the dispatcher. If you feel faint, lie flat with your legs elevated. The dizziness usually passes within a few minutes.
Should I chew aspirin if I am already on a blood thinner?
No. If you take warfarin, apixaban, rivaroxaban, or another blood thinner prescribed by your doctor, do not take aspirin without asking your doctor first. Tell the paramedics what blood thinner you take so they know your full medication list.
What if I do not have nitroglycerin at home?
Call 911 when ready. Do not wait for someone to get nitroglycerin for you. Paramedics carry nitroglycerin and other heart medications and can give them to you in the ambulance. The sooner you call, the sooner they can reach you.