Nitroglycerin (Oral, Sublingual)


Nitroglycerin in oral/sublingual forms helps people with coronary artery disease. This is when plague deposits build up in the arteries and decreases blood flow. The decrease in blood flow causes chest pain, known as angina, and a complete blockage in the artery may cause a heart attack. The medication relaxes and widens the blood vessels so they flow freely through the blocked arteries which, in turn, eases angina and stops the chest pain.

Nitroglycerin as a medication is an organic nitrate that includes 5 percent dextrose (sugar derived from corn). The dextrose stops the nitroglycerin from being explosive. When taken orally, the medication quickly relaxes the blood vessels so they can flow through the clogged arteries faster to bring much needed blood and oxygen to the heart.

Oral forms of nitroglycerin are mostly prescribed by doctors for when-needed use. That is it is taken when angina occurs or is about to occur. The drug is intended for use as soon as angina occurs or right before facing a stressful situation to prevent angina from happening at all. There is a daily tablet to prevent chest pain altogether that must be taken regularly. Patients should talk to a doctor about which form would be best to deal with angina. For example, a patient that experiences angina often might benefit from daily extended releases tablets.

The medication has several necessary side effects that might make a person worry, but they are actually signs that the medicine is working properly. Nitroglycerin has several potentially dangerous drug interactions so it is important to tell a physician of any health problems or medications before starting the medication. When taken properly, Nitroglycerin can relive angina in mere minutes.

Common brand names include:

  • Nitrocot
  • Nitrolingual
  • NitroMist
  • NitroQuick
  • Nitrostat
  • Nitrotab
  • Nitro-Time

Conditions Treated

  • Angina Pectoris

Type Of Medicine

  • Nitrate

Side Effects

Nitroglycerin has several side effects that are actually signs that the medication is doing its job and working properly. The most common side effect is a headache. Up to 64% of patients taking nitroglycerin experience mild to severe headaches. Ask a doctor before taking any pain medication to deal with the headache as some pain relievers might have negative interactions with the drug. The physician may prescribe over the counter pain relievers such as acetaminophen to lessen headache pain. Massaging the temples might help lessen the pain until it passes. Try a hot or cold back on the forehead or neck to relive headache pain. Avoiding bright lights, such as from a TV or computer, can also help relieve head pain. Rest in a dark room until it passes. However, the headache should pass not long after the angina stops.

The second most common side effect is dizziness or even fainting. Up to 10% of patients will experience lightheadedness, dizziness, or fainting. Like headaches, this is a sign the medicine is working and not a cause for concern. It is recommended to sit or lay down before taking nitroglycerin to prevent falls or to relieve the lightheadedness. Do not get up until the symptoms completely pass. Try staring at a spot on the wall or ceiling which can trick the brain into realizing the body is not moving. When symptoms end, sit up slowly and wait to make sure dizziness does not return before standing up just as slowly. If lightheadedness reoccurs, sit back down and try again after a short rest. Dizziness is more likely to occur in hot weather, while drinking alcohol, or while exercising. Do not drive or operate machinery after taking nitroglycerin. Older patients have a higher risk of dizziness and lightheadedness. This creates a larger risk of falls. Patients should remain sitting at all times until the feeling passes.

There is a rare chance of allergic reaction when taking this medication. Get emergency medical help if any symptoms of an allergic reaction occur as it could be life threatening. Signs of an dangerous allergic reaction include:

  • Cracked or scaly skin

Common side effects often go away once the body is used to the medicine. Nausea or vomiting is one such common side effect. Up to 10% of patients taking nitroglycerin will experience nausea but it should go away over time once the system has gotten used to the drug. When experiencing any of these side effects do not stop taking the medication. If the problems persist, patients should talk to a doctor. They might be able to prescribe additional medication to fight the side effects. Do not take medication not prescribed by the doctor as many drugs have bad interactions with nitroglycerin. Common side effects that should go away after a time include:

  • Blurred vision

Nitroglycerin can also cause several unwanted side effects that might not go away over time. Contact a medical professional if these side effects occur while taking the medication. The doctor may be able to prescribe safe medicines to eliminate the side effects or prescribe a different medication for angina. The doctor can also provide medication-free techniques to deal with the side effects. Only take medicines prescribed by the doctor as many have bad interactions with nitroglycerin. Common unwanted side effects with nitroglycerin include:

  • Pins and needles or tingling of the skin


Oral and sublingual nitroglycerin medication comes in four types. Each type has a certain dosage and proper way to take it. While there are common dosage amounts for all types, a doctor might prescribe a smaller or larger amount. Always take the dosage as prescribed by the doctor and written on the bottle. While the amount might change, how nitroglycerin is taken in the various forms remains the same. Do not keep taking nitroglycerin if the doctor says to stop, even if medication still remains. There is a reason the doctor stopped usage.

Extended release tablets: Extended release tablets are taken every day on a set schedule as prescribed by the doctor. The tablets keeps the nitroglycerin in the system to prevent angina attacks from occurring. It is recommended to take the pills around the same time every day, usually first thing in the morning. If a dose is missed, it should be taken right away unless it is close to the regular time to take the next dose. In that case, completely skip the missed dose as taking double could cause an overdose. Do not cut, crush, or dissolve the tablets as that can lessen medication effectiveness. Always swallow the tablets whole.

Common dosage amount: 2.5 to 6.5 milligrams taken 3 to 4 times daily.

Oral spray: Oral spray is meant to be taken when angina occurs or if a patient is about to face a stressful event or do exercise in which angina might occur. When taking the spray, sit up straight, tilt head back, and lift the tongue. Hold the bottle upright and press the release button for 1 or 2 sprays so that the medicine land under the tongue. It is best to spray under the tongue as it will dissolve into the system the fastest. Do not swallow for at least 5 minutes to give the drug time to dissolve completely. Spray 5 to 10 minutes before an activity to prevent angina. If symptoms persist after 5 minutes when angina has already begun, do another spray. Do not take more than 3 sprays in 15 minutes. If the chest pains do not go away, emergency medical treatment will be necessary.

Common dosage amount: 0.4 to 0.8 milligrams per spray taken every 5 minutes with no more than 3 in a 15 minute span of time.

Sublingual tablet: Sublingual means "under the tongue."Instead of swallowing this tablet, it is placed beneath the tongue and left to dissolve. Sit down before taking the medication because it may cause dizziness. Take a tablet 5 to 10 minutes before any strenuous activity to prevent chest pains from starting or take it once angina begins. Place a single tablet under the tongue or between the cheek and gums. Do not crush or chew the tablet. Do not drink or eat anything while waiting for the tablet to dissolve. It will dissolve quickly and enter the system to relieve angina. If pain persists after 5 minutes, take another tablet. It is safe to take 3 tablets within a 15 minute period. Do not take more because it could cause an overdose.

Common dosage amount: 0.3 to 0.6 milligrams per tablet taken every 5 minutes with no more than 3 tablets in a 15 minute span of time.

Sublingual powder: Sublingual powder is placed beneath the tongue so that it dissolves and enters the blood stream quickly. Nitroglycerin comes in individual packets with powder inside. If taking the medication to prevent angina during a stressful activity, take 1 or 2 packets 5 to 10 minutes before the activity begins. If taking nitroglycerin to stop angina that has already begun, take 1 or 2 packets right away. Sit down before taking the medication to help with dizziness. Open the packet, open mouth, tilt head back, lift the tongue, and dump the powder directly under the tongue. The medicine will start working within 1 to 5 minutes. If pain persists after 5 minutes, take another packet. Do not take more than 3 packets in a 15 minute span of time or overdose may occur.

Common dosage amounts: 0.4 milligrams per packet taken every 5 minutes with no more than three packets in a 15 minute span of time.

There are no recommended dosage amounts of nitroglycerin for children. A doctor can prescribe nitroglycerin for children but the dosage amount will be much smaller. Always follow the dosage amount strictly when it comes to children as there is an much higher risk of overdose. Thoroughly discuss allowing a child to take nitroglycerin with the doctor before agreeing to the medication as there might be other options available.


Many medications have unwanted interactions with each other. This means they affect how well the drug works. There are several medications that should never be taken with nitroglycerin as it will lessen the effectiveness or make it not work at all. Other medications might have mild interactions but a doctor might still prescribe them alongside the nitroglycerin. Doctors feel that the good the medicine will do is more important than any mild side effects.

It is important to tell physicians about any medications taken. This includes both prescription medications from another doctor or over the counter medicines that patients decide to take on their own. Tell the physician about any of these drugs as they have the greatest risk of negative interaction with nitroglycerin:

  • Erectile Dysfunction medications including avanafil (Stendra, Spedra), sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra)

Medications that a doctor might prescribe alongside nitroglycerin or will allow patients to continue taking despite potential mild interactions include:

  • Ergot migraine medications including ergotamine (Cafergot, Ergomar), dyhydroergotamine (Migranal), and methylergonovine (Methergine)


Safety precautions are important when taking medications. While the drug is designed to help a specific problem it can also potentially cause problems. In order to prevent health problems, patients must inform doctors of all medical issues, allergies, and prescriptions. Listen to the doctor's explicit advice. Nitroglycerin will help the best when taken properly and safely.

It is important for a patient to tell the doctor about any allergies to similar medications that are used to treat angina. One example is isosorbide mononitrate. An allergy to one nitrate means there is a greater risk of an allergic reaction to another. Also, a patient should tell a doctor about all medical history that might affect the medication or cause greater side effects. Nitroglycerin might cause some medical issues to become worse and should not be taken for that reason. Medical issues that might affect effectiveness or become worse when taking nitroglycerin include:

  • Recent head injury

Patients should tell the doctor about any drinking or recreational drugs without feeling ashamed. This include drugs taken at that time and in the past, especially if the patient has had a past addiction. Doctor confidentiality will protect the patient and possibly save their lives as nitroglycerin may interact with recreational drugs or alcohol. In fact, alcohol can greatly increase the dizziness that is common when taking nitroglycerin.

Nitroglycerin should only be taken by pregnant women if the doctor feels it will be safe. If a patient becomes pregnant while taking nitroglycerin they should continue to do so but talk to the doctor as soon as possible. The physician will decide if the mother-to-be should keep taking the drug or not. It is not known if the medication passes into breast milk. It is recommended to discuss this issue with a doctor before beginning breast feeding while taking nitroglycerin.

Like many medications, sublingual nitroglycerin tablets, sprays, and powders can stop working when taken too often. The body becomes immune to its effects. This is called medication tolerance. Only take the drug when truly necessary to prevent this from happening. If angina occurs often, a doctor might suggest taking the extended release tablets instead. These, too, have a risk of medication tolerance. Doctors reduce this risk by giving the patient drug-free periods during the day when they are not taking any of the medication. It is important for patients to follow the recommended dosage timeline as it will help prevent tolerance and keep the medication working properly.

Do not stop taking extended release nitroglycerin tablets without talking to a doctor first. The physician might suggest gradually reducing the amount of medication to prevent any side effects. This allows the body to get used to the loss of the medication but still function without issues.

Older patients with liver, kidney, or heart problems have a greatest risk of problems with nitroglycerin. Discussing all health issues with a doctor before taking the drug will help the doctor determine if nitroglycerin will be more helpful or harmful.

There is a high risk of overdose if nitroglycerin is not taken properly. Oral sprays, sublingual tablets, and sublingual powders have a strict dose limit. Do not take more than three doses in a 15 minute span of time. Doing so may cause an overdose. An overdose from nitroglycerin has many symptoms. If a patients experience a few of these symptoms after taking too much nitroglycerin it should be considered a medical emergency. A patient who has overdose will often lose consciousness, have difficulty breathing, experience double vision, and have flushed, cold skin. While headaches are common when taking this medication, a sign of an overdose is a severe, throbbing headache that causes overbright appearance of lights, halos around lights, disturbed color perception, and blurred vision. There are many other signs of overdose. Get to a hospital if any of these other overdose symptoms occur:

  • Dark urine


Proper storage for nitroglycerin depends on the type. It is important to keep the medications safe and away from children. If a patient no longer needs the medication, a doctor will provide information on properly and safely disposing of the drug. Do not just throw it into the garbage as many medications will leak into the ground in landfills.

Extended release tablets should be kept inside the bottle with the lid tightly closed. Store it in a medicine cabinet or room away from heat and moisture. Do not place the tablets in direct sunlight as it will heat them up.

Do not open sublingual powder packets until needed. Keep the packets in a medicine cabinet or drawer away from heat and direct light. Do let the packets become wet as the powder will dissolve.

Sublingual tablets should be kept in the original packaging until needed. Make sure the lid is on tightly. Keep the bottle in a medicine cabinet or other location away from heat, moisture, and direct light.

Keep the cover on oral spray bottles until the medication is needed. Store the bottle in an upright position and not on the side or upside down. Keep it away from heat or cold as they are high pressure bottles that can burst. Do not burn empty spray bottles. Do not try to freeze the medication.


Nitroglycerin helps to relieve chest pain caused by coronary artery disease, but it really does much more than that. It can help prevent a heart attack by relaxing the blood vessels so they pass through the arteries without a problem. If the artery becomes completely blocked it will cause a heart attack that could be lethal. While the medication is beneficial to so many people with heart problems, it is still a dangerous drug that has many bad interactions with other medications and a high risk of overdose. Patients should talk thoroughly with a doctor about all medical problems, health issues, and medications so that the patient can receive the correct dosage. Always follow the dosage amount and doctor's dosage timeline to prevent overdose and medication tolerance.

When taken correctly and at the right time, nitroglycerin can stop chest pain within mere minutes from onset. By placing the medication under the tongue, it dissolves and absorbs very quickly into the blood stream so that it can put a stop to angina right away. While it causes side effects such as headaches and dizziness while taking the medication, those issues are short-lived and mild compared to a deadly heart attack. Because nitroglycerin is mostly taken when an angina attack already starts, patients should keep it on hand at all times. Place it in a bag, purse, or wallet when leaving home. In the house, keep it within easy reach in a drawer near a favorite sitting spot. Keeping the nitroglycerin powder, oral spray, or sublingual tablets at hand can save a life.