Isosorbide dinitrate is used to prevent angina (chest pain) caused by coronary artery disease. It does not work fast enough to relieve the pain of an angina attack that has already started.

Isosorbide dinitrate 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, this helps prevent angina attacks from occurring.

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

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 form of nitrate is used to reduce the number of angina attacks over a long time. It will not relieve an attack that has already started because it works too slowly. The extended-release form releases medicine gradually to provide its effect for 8 to 10 hours. Check with your doctor if you also need a fast-acting medicine to relieve the pain of an angina attack.

You should take this medicine 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.

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 and let it dissolve there. Do not eat, drink, smoke, or use chewing tobacco while a tablet is dissolving.

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

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:

Rare

Bluish-colored lips, fingernails, or palms

dark urine

difficulty with breathing

dizziness or lightheadedness

fever

headache

pale skin

rapid heart rate

sore throat

unusual bleeding or bruising

unusual tiredness or weakness

Incidence not known

Arm, back, or jaw pain

blurred vision

chest pain or discomfort

chest tightness or heaviness

confusion

dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position

fainting

fast or irregular heartbeat

sweating

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

Symptoms of overdose

Blurred or loss of vision

bulging soft spot on the head of an infant

change in consciousness

change in the ability to see colors, especially blue or yellow

cold, clammy skin

convulsions

disturbed color perception

double vision

fast, irregular, pounding, or racing heartbeat or pulse

feeling of constant movement of self or surroundings

halos around lights

headache, severe and throbbing

increased sweating

loss of appetite

loss of consciousness

nausea

night blindness

overbright appearance of lights

paralysis

sensation of spinning

slow heartbeat

tunnel vision

vomiting

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.

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 that 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 experience 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 faintness may occur, especially when you get up quickly from a lying or sitting position. Getting up slowly may help.

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.