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Gen-Nitro

Generic name: nitroglycerin (oral route, sublingual route)
Drug classes: Antianginal agents, Vasodilators

Medically reviewed by Drugs.com. Last updated on Dec 14, 2023.

Commonly used brand name(s)

In the U.S.

In Canada

Available Dosage Forms:

Therapeutic Class: Antianginal

Chemical Class: Nitrate

Uses for Gen-Nitro

Nitroglycerin is used to prevent angina (chest pain) caused by coronary artery disease. This medicine is also used to relieve an angina attack that is already occurring.

Nitroglycerin belongs to the group of medicines called nitrates. It works by relaxing the blood vessels and increasing the supply of blood and oxygen to the heart while reducing its work load. When used regularly on a long-term basis, or just before exercise or a stressful event, this helps prevent angina attacks from occurring.

This medicine is available only with your doctor's prescription.

Before using Gen-Nitro

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of nitroglycerin in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of nitroglycerin in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving nitroglycerin.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Proper use of Gen-Nitro

This section provides information on the proper use of a number of products that contain nitroglycerin. It may not be specific to Gen-Nitro. Please read with care.

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

This medicine comes with a patient information insert. Read and follow the instructions in the insert carefully. Ask your doctor if you have any questions.

Nitroglycerin is available as two types of products that are used for different reasons. The extended-release capsules are used every day on a specific schedule to prevent angina attacks. The oral spray, sublingual powder, and sublingual tablets work quickly to stop an angina attack that has already started or they can be used to prevent angina if you plan to exercise or expect a stressful event.

When you begin to feel an attack of angina starting (chest pains, tightness or squeezing in the chest), sit down. Then place a sublingual powder or tablet in your mouth or under your tongue. If you use the oral spray, you should spray it on or under the tongue. You may become dizzy, lightheaded, or faint soon after using a tablet or spray, so it is safer to sit rather than stand while the medicine is working. If you become dizzy or faint while sitting, take several deep breaths and bend forward with your head between your knees. Remain calm and you should feel better in a few minutes.

If you are taking the nitroglycerin sublingual powder: Empty the contents of a packet under your tongue. Close your mouth and breathe normally. Allow powder to dissolve without swallowing. Do not rinse or spit for 5 minutes after taking this medicine. Do not take more than 3 packets in 15 minutes. If you still have pain after you take a total of 3 packets, this is an emergency. Call 911. Do not drive yourself to the hospital.

Nitroglycerin sublingual tablets should not be chewed, crushed, or swallowed. They work much faster when absorbed through the lining of the mouth. Place the tablet under the tongue or between the cheek and gum, and let it dissolve. Do not eat, drink, smoke, or use chewing tobacco while a tablet is dissolving.

Nitroglycerin sublingual tablets usually give relief in 1 to 5 minutes. However, if the pain is not relieved, you may use a second tablet 5 minutes after you take the first tablet. If the pain continues for another 5 minutes, a third tablet may be used. If you still have chest pain after a total of 3 tablets, contact your doctor or go to a hospital emergency room right away. Do not drive yourself and call 911, if necessary.

You may administer 1 or 2 sprays of Nitroglycerin oral spray at the onset of chest pain. If the pain continues after 5 minutes, a third spray may be used. You must wait 5 minutes after the first 1 or 2 sprays before using a third spray. If you still have chest pain after a total of 3 sprays, contact your doctor or go to a hospital emergency room right away. Do not drive yourself and call 911 if necessary. Do not use more than 3 sprays in a 15-minute period.

Swallow the extended-release capsule whole. Do not split, crush, or chew it.

You should take the extended-release capsule first thing in the morning and follow the same schedule each day. This medicine works best if you have a "drug-free" period of time every day when you do not take it. Your doctor will schedule your doses during the day to allow for a drug-free time. Follow the schedule of dosing carefully so the medicine will work properly.

To use the oral spray:

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the extended-release capsules in a closed container at room temperature, away from heat, moisture, and direct light.

Store the sublingual powder at room temperature, away from heat, moisture, and direct light.

Sublingual tablets should be kept in the original glass bottle. Screw the cap on tightly after each use and store the bottle at room temperature, away from heat, moisture, and direct light.

Store the oral spray at room temperature, away from heat and direct light. Do not freeze. Do not keep this medicine inside a car where it could be exposed to extreme heat or cold. Do not forcefully open the container or throw it into a fire, even if it is empty.

Precautions while using Gen-Nitro

If you will be taking this medicine for a long time, it is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not take avanafil (Stendra®), riociguat (Adempas®), sildenafil (Viagra®), tadalafil (Cialis®), or vardenafil (Levitra®) while you are using this medicine. Using these medicines together may cause blurred vision, dizziness, lightheadedness, or fainting. If you are taking these medicines and you have an angina attack, you must go to the hospital right away.

This medicine may cause headaches. These headaches are a sign that the medicine is working. Do not stop using the medicine or change the time you use it in order to avoid the headaches. If you have severe pain, talk with your doctor.

Dizziness, lightheadedness, or fainting may occur, especially when you get up quickly from a lying or sitting position. Getting up slowly may help. Also, lying down for a while may relieve dizziness or lightheadedness.

Dizziness, lightheadedness, or fainting is also more likely to occur if you drink alcohol, stand for long periods of time, exercise, or if the weather is hot. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for long periods of time.

Do not stop using this medicine without checking first with your doctor. Your doctor may want you to gradually reduce the amount you are using before stopping it completely.

Blurred vision or dryness of the mouth may occur while using this medicine. Check with your doctor if this concerns you.

Serious skin reactions can occur with this medicine. Check with your doctor right away if you have cracks in the skin, feeling of warmth, loss of heat from the body, rash, red, swollen skin, redness of the face, neck, arms, and occasionally, upper chest, or scaly skin while you are using this medicine.

Make sure any doctor or dentist who treats you knows that you are using this medicine. You may need to stop using this medicine several days before you have medical tests.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Gen-Nitro side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

Rare

Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.