How long does nitroglycerin last in your system?

Heart Medication: Nitroglycerin

You have probably heard about the little white nitroglycerin pills that heart disease patients slip under their tongues when they experience symptoms of a heart attack.

The effects of nitrates taken under the tongue, as sublingual nitroglycerin, only last about 5 to 10 minutes or so. Longer-lasting nitroglycerin and other nitrate compounds also can be taken to prevent angina — chest pain. Chest pain or pressure can occur when the heart is not getting enough blood. It is a common symptom of coronary artery disease or heart disease.

“Nitroglycerin also is given to some patients with chronic or congestive heart failure, particularly in combination with hydralazine,” a blood pressure medication, says Christopher P. Cannon, MD, associate professor of medicine at Harvard Medical School.

Nitroglycerin comes in many forms, including:

  • Tablets: NitroQuick, Nitro-Tab, Nitrostat
  • Spray: Nitrolingual
  • Capsules: Nitro-Time
  • Patch: Nitro-Dur

How Does Nitroglycerin Work?

Nitroglycerin can alleviate chest pain by relaxing the muscles in the walls of the blood vessels, causing them to dilate. Opening or widening blood vessels results in improved blood flow to the heart. “Also, by dilating veins, nitrates reduce the flow of blood returning to the heart, which reduces the workload or pressure placed on the heart,” Dr. Cannon says.

For best results, take nitroglycerin in the morning on an empty stomach. Having a nitrate-free period overnight can help avoid your developing a tolerance to the medication (where you do not see as much of a benefit), which can be an issue, Cannon advises. Never chew, crush or open nitroglycerin capsules.

Side Effects of Nitroglycerin and Other Nitrates

Headaches, sometimes severe and resembling migraines, are very common when starting a nitroglycerin regimen. But most people find they go away after the first few weeks.

Other side effects include:

  • Dizziness
  • Fainting, due to a drop in blood pressure
  • Chest pain
  • Difficulty breathing
  • Blurred vision
  • Problems swallowing
  • Nausea
  • Weakness
  • Sweating
  • Increase in heart rate, called tachycardia

Pros and Cons of Nitroglycerin as a Heart Medication

Nitroglycerin is effective in treating chest pain in some people. The longer-lasting pills may prevent angina from occurring in the first place, and when combined with a blood pressure medication, nitrates can be used for patients with heart failure who cannot tolerate angiotensin-converting enzyme inhibitors.

But there are also cons. As previously mentioned, patients can develop a tolerance to nitroglycerin after using the drug for some time or taking many doses. Also, some of those side effects — chest pain, difficulty breathing or swallowing, nausea, weakness, and sweating — can be serious.

And nitroglycerin should not be used if drugs for erectile dysfunction have been taken in the last 24 to 48 hours. “Men who are taking medication for erectile dysfunction should not take nitrate medications such as nitroglycerin, or vice versa, because the combination can cause a serious decrease in blood pressure, which could lead to fainting, stroke, or heart attack,” Cannon says.

Nitroglycerin has been used for some time to treat acute chest pain and to prevent chest pain from occurring. But that doesn’t mean it can’t interact with newer medications. Always ask your doctor about the medicines that are best for you and your condition.

Learn more in the Everyday Health Heart Health Center.

  • Medicines to treat high blood pressure.
  • Certain heart medicines.
  • Over-the-counter cough, cold, and flu medicines.
  • Over-the-counter herbal cough, cold, and flu medicines.
  • Speak to your doctor or pharmacist about any other information you may need to know about your medications.

    What else should I tell my doctor?

    Always give your doctor your complete medical history, especially if you are over 60 years of age, have recently had a stroke or heart attack or have severe headaches, low iron (anemia) or glaucoma. You may also want to talk to your doctor about how effective nitrates are for managing your angina. Your doctor can adjust the amount of medicine or suggest other ways of managing your condition.

    What are some side effects?

    Some common side effects of nitrates include headaches, flushing, dizziness, fainting, low blood pressure (hypotension) and irregular heart rhythms (arrhythmia). Report any and all side effects to your doctor.

    Lifestyle changes

    Eating a healthy diet that is lower in fat, especially saturated and trans fats, being smoke free, limiting alcohol use, being physically active and reducing stress are also important in lowering the risk of heart disease. Talk to your healthcare practitioner about how you can achieve these lifestyle changes.

    Related information

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    Your ministry of health also provides useful health resources in your province or territory. For example, Ontario’s MedsCheck program provides free pharmacist consultations on safety use of drugs. And British Columbia’s Senior Healthcare webpage provides information about important health programs.

    Drug coverage

    Nitroglycerin: 6 things you should know

    3. Downsides

    If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

    • Dizziness, light-headedness, headache, and low blood pressure may occur. This may affect a person’s ability to drive or operate machinery. Alcohol, hot weather, and exercise may worsen these effects and result in fainting. Blurred vision may also occur.
    • Rarely, allergic reactions, flushing, severe dizziness, a headache, or persistent nausea or vomiting may occur. Seek urgent medical help.
    • Alcohol toxicity has been reported when high-dose nitroglycerin injection has been given in conjunction with alcohol, or when certain medications (such as disulfiram, cephalosporin antibiotics) are taken at the same time as nitroglycerin and alcohol. Do not drink alcohol while using nitroglycerin.
    • Tolerance can develop to nitroglycerin’s effect (tolerance is when the same dose no longer produces the same effect). To prevent this from developing, nitroglycerin-free intervals of 10-12 hours between doses are recommended. However, if you are experiencing chest pain, which is unrelieved by one nitroglycerin dose, it is acceptable to have another dose and call for urgent medical help.
    • May not be suitable for some people including seniors; those with a history of stroke or bleeding in the brain; with anemia, glaucoma, migraines, or swelling of the heart sac; taking medications for erectile dysfunction; or in people whose blood flow back to the heart is already restricted.
    • May interact with a number of other medications including medicines used to treat erectile dysfunction (such as sildenafil and tadalafil), topical anesthetics, antidepressants and antipsychotics, riociguat, diuretics, ergot derivatives, and tizanidine. Alcohol may increase the side effects of nitroglycerin. May affect the results of some medical tests.
    • Nitroglycerin can be toxic to children and pets. Keep well out of reach.

    Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, .

    Nitroglycerin sublingual tablets

    What is this medicine?

    NITROGLYCERIN (nye troe GLI ser in) is a type of vasodilator. It relaxes blood vessels, increasing the blood and oxygen supply to your heart. This medicine is used to relieve chest pain caused by angina. It is also used to prevent chest pain before activities like climbing stairs, going outdoors in cold weather, or sexual activity.

    This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

    COMMON BRAND NAME(S): Nitroquick, Nitrostat, Nitrotab

    What should I tell my health care provider before I take this medicine?

    They need to know if you have any of these conditions:

    • anemia

    • head injury, recent stroke, or bleeding in the brain

    • liver disease

    • previous heart attack

    • an unusual or allergic reaction to nitroglycerin, other medicines, foods, dyes, or preservatives

    • pregnant or trying to get pregnant

    • breast-feeding

    How should I use this medicine?

    Take this medicine by mouth as needed. At the first sign of an angina attack (chest pain or tightness) place one tablet under your tongue. You can also take this medicine 5 to 10 minutes before an event likely to produce chest pain. Follow the directions on the prescription label. Let the tablet dissolve under the tongue. Do not swallow whole. Replace the dose if you accidentally swallow it. It will help if your mouth is not dry. Saliva around the tablet will help it to dissolve more quickly. Do not eat or drink, smoke or chew tobacco while a tablet is dissolving. If you are not better within 5 minutes after taking ONE dose of nitroglycerin, call 9-1-1 immediately to seek emergency medical care. Do not take more than 3 nitroglycerin tablets over 15 minutes.

    If you take this medicine often to relieve symptoms of angina, your doctor or health care professional may provide you with different instructions to manage your symptoms. If symptoms do not go away after following these instructions, it is important to call 9-1-1 immediately. Do not take more than 3 nitroglycerin tablets over 15 minutes.

    Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

    Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

    NOTE: This medicine is only for you. Do not share this medicine with others.

    What if I miss a dose?

    This does not apply. This medicine is only used as needed.

    What may interact with this medicine?

    Do not take this medicine with any of the following medications:

    • certain migraine medicines like ergotamine and dihydroergotamine (DHE)

    • medicines used to treat erectile dysfunction like sildenafil, tadalafil, and vardenafil

    • riociguat

    This medicine may also interact with the following medications:

    • alteplase

    • aspirin

    • heparin

    • medicines for high blood pressure

    • medicines for mental depression

    • other medicines used to treat angina

    • phenothiazines like chlorpromazine, mesoridazine, prochlorperazine, thioridazine

    This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

    What should I watch for while using this medicine?

    Tell your doctor or health care professional if you feel your medicine is no longer working.

    Keep this medicine with you at all times. Sit or lie down when you take your medicine to prevent falling if you feel dizzy or faint after using it. Try to remain calm. This will help you to feel better faster. If you feel dizzy, take several deep breaths and lie down with your feet propped up, or bend forward with your head resting between your knees.

    You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this drug affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol can make you more drowsy and dizzy. Avoid alcoholic drinks.

    Do not treat yourself for coughs, colds, or pain while you are taking this medicine without asking your doctor or health care professional for advice. Some ingredients may increase your blood pressure.

    What side effects may I notice from receiving this medicine?

    Side effects that you should report to your doctor or health care professional as soon as possible:

    • blurred vision

    • dry mouth

    • skin rash

    • sweating

    • the feeling of extreme pressure in the head

    • unusually weak or tired

    Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

    • flushing of the face or neck

    • headache

    • irregular heartbeat, palpitations

    • nausea, vomiting

    This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

    Where should I keep my medicine?

    Keep out of the reach of children.

    Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Store in original container. Protect from light and moisture. Keep tightly closed. Throw away any unused medicine after the expiration date.

    NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

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    BRAND NAME(S): Nitrostat

    Medication Uses | How To Use | Side Effects | Precautions | Drug Interactions | Overdose | Notes | Missed Dose | Storage

    USES: This medication is used before physical activities (such as exercise, sexual activity) to prevent chest pain (angina) in people with a certain heart condition (coronary artery disease). It may also be used to relieve chest pain in these people once it occurs.Nitroglycerin belongs to a class of drugs known as nitrates. Angina occurs when the heart muscle is not getting enough blood. This drug works by relaxing and widening blood vessels so blood can flow more easily to the heart.

    HOW TO USE: Ask your doctor now for exact instructions on how to use your nitroglycerin and when to call for emergency medical help (911).Read the Patient Information Leaflet if available from your pharmacist before you start using nitroglycerin and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Sit down before using this medication. Place 1 tablet under the tongue and allow it to dissolve as directed by your doctor. Do not chew or swallow the tablet. The dosage is based on your medical condition and response to treatment.If you are using this medication to prevent chest pain before physical activities, use it 5 to 10 minutes before the activity.If you are using this medication to relieve chest pain once it occurs, use it as soon as possible. If your chest pain has not improved or if it has worsened 5 minutes after you use this drug, call emergency medical help (911). After calling the emergency number, use another dose. Five minutes after the second dose, if you still have chest pain and the ambulance has not arrived, use a third dose. If your chest pain is not gone after 15 minutes and 3 doses of nitroglycerin, call emergency medical help (911) if you have not called already. Do not use more than 3 doses during an attack unless directed by your doctor.

    SIDE EFFECTS: Headache, dizziness, lightheadedness, nausea, flushing, and burning/tingling under the tongue may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Headache is often a sign that this medication is working. Your doctor may recommend treating headaches with an over-the-counter pain reliever (such as acetaminophen, aspirin). If the headaches continue or become severe, tell your doctor promptly.To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor immediately if these unlikely but serious side effects occur: fainting, fast/irregular/pounding heartbeat.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

    Continuous dose of nitroglycerin increases severity of heart attacks, study shows

    Daria Mochly-Rosen

    When given for hours as a continuous dose, the heart medication nitroglycerin backfires — increasing the severity of subsequent heart attacks, according to a study of the compound in rats by researchers at the Stanford University School of Medicine.

    “Basically it’s a cautionary tale,” said professor of chemical and systems biology Daria Mochly-Rosen, PhD, senior author of the study published Nov. 2 in Science Translational Medicine. “Here is a practice in medicine used for over 100 years. Nitroglycerin is so old that a proper clinical trial has never been formally done. Our study says it’s time for cardiologists to examine the value of nitroglycerin treatment that extends for hours at a time.”

    The study also showed that the damage can be reduced by simultaneous treatment with an enzyme activator known as Alda-1, discovered by Mochly-Rosen and collaborators and reported in Science in 2008.

    Nitroglycerin is a mainstay of care for heart disease. It’s the go-to medicine for those suffering from bouts of chest pain, known as angina pectoris, who take it as a sublingual tablet or oral spray. And it’s a standard treatment for heart attack patients, who get it also through an I.V. drip or patch in the emergency room.

    It works like a charm, at least at first, opening vessels so blood can flow to the heart more easily. But sustained use leads to desensitization, a pitfall noticed shortly after the explosive chemical was first used as a drug, in 1867 — the same year Alfred Nobel obtained his patents for dynamite, which had nitroglycerin as its main ingredient.

    To reduce desensitization to nitroglycerin, modern physicians cycle patients on and off the drug: A typical regimen for hospitalized heart attack patients is 16 hours on, eight hours off. An occasional tablet or spritz is not known to lead to this dampened response.

    What wasn’t suspected until the last decade was that prolonged use of nitroglycerin could actually harm heart tissue if a heart attack occurs. Among the evidence are observations that nitroglycerin damages cells in the heart by wrecking an important enzyme, ALDH2, which not only mops up toxic products of free radicals, but is the key to nitroglycerin’s ability to stave off chest pain. ALDH2 catalyzes the conversion of nitroglycerin to nitric oxide, which reduces chest pain by opening the blood vessels. So by damaging ALDH2, nitroglycerin shoots itself in the foot as a heart disease treatment.

    In 2008, Mochly-Rosen and colleagues identified another function of ALDH2: It’s a critical enzyme for protecting the heart from damage caused by ischemia, or decreased blood flow — not just for people being treated with nitroglycerin, but for everyone. So the researchers too became concerned about the safety of sustained nitroglycerin use.

    “We knew that nitroglycerin was an important treatment for heart attack symptoms,” said Mochly-Rosen, who is also the George D. Smith Professor in Translational Medicine and a member of the Stanford Cardiovascular Institute. “And we thought, ‘Wait, everyone gets nitroglycerin when they come to the emergency room with chest pains, sometimes in a drip or as a patch. What if they get a heart attack during this period? It could be more severe than if they had not been treated.’”

    That led to their current study. Using a rat model, they tested the effect of sustained nitroglycerin treatment on the severity of heart attacks. They found that nitroglycerin increased heart attack severity in rats. After 16 hours of nitroglycerin treatment, the heart damage was twice as large as in untreated control animals. Five to eight animals made up each group.

    Cardiac function was also significantly diminished in relation to the control animals, as determined by echocardiograms immediately after the heart attack and again two weeks later. And when the rats were given the enzyme activator Alda-1 along with nitroglycerin, the detrimental effects of prolonged nitroglycerin treatment were nearly erased.

    “We showed unequivocally that the rats were worse off after nitroglycerin treatment, and if we had Alda-1 on board, we protected them,” said Mochly-Rosen.

    “Nitroglycerin improves blood flow when the vessels are constricting. But what we found is that if you use it for too long, the enzyme that helps protect against tissue damage — ALDH2 — dies. With our animal model, we demonstrated that the loss of this enzyme makes the outcome from the heart attack worse. Nitroglycerin is not benign.”

    Given the importance of ALDH2 in protecting different tissues, including the heart, nitroglycerin tolerance should not be considered as a simple loss of drug efficacy, said co-author Julio Cesar Batista Ferreira, PhD, a postdoctoral scholar. “Our study was the first to show the nitroglycerin tolerance is associated with increased cardiac vulnerability. Further studies to identify the molecular mechanisms of nitroglycerin tolerance and its side effects are needed.”

    Alternative treatments to improve blood flow in cardiac patients exist, said cardiologist John Cooke, MD, PhD, a Stanford professor of cardiovascular medicine who was not involved in the study but has discussed it with the researchers.

    “Continuous administration of nitroglycerin by patch or by intravenous infusion, as in the coronary care unit, is initially useful in relieving pain and also favorably influences hemodynamics — reduces blood pressure, improves coronary blood flow. However, extended use of this form of nitroglycerin is known to induce tolerance to its own beneficial actions within 12 to 24 hours,” said Cooke, adding that researchers don’t yet know the full effects of using the drug for more than 24 hours.

    “Professor Mochly-Rosen’s work raises additional concern about the extended use of long-acting or continuous administration of nitroglycerin in the coronary care unit,” he added. “It is probably best to use nitroglycerin continuously for only short periods of time, and replace the continuous infusion or patch with other medications to reduce symptoms and favorably influence hemodynamics.”

    In the future, said Mochly-Rosen, the hazards of nitroglycerin could be eliminated by pairing it with Alda-1, if it is proven safe in humans, or another drug with a similar enzyme-activating function.

    Mochly-Rosen’s collaborators were Ferreira and first author Lihan Sun, PhD, a former graduate student.

    The research was supported by the National Institute on Alcohol Abuse and Alcoholism and the São Paulo Research Foundation. A patent has been filed by Stanford University for the therapeutic use of Alda-1 to target ALDH2 and treat myocardial ischemia. Mochly-Rosen is the founder of ALDEA Pharmaceuticals Inc. and KAI Pharmaceuticals Inc., which she reports have no current plans to develop products in connection with this research.

    Information about Stanford’s Department of Chemical and Systems Biology, which also supported the work, is available at

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