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

Isosorbide mononitrate 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 workload. 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 gradually releases medicine 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.

Swallow the extended-release tablet whole with a half glass of water. 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:

Less common

Abnormal heart sound

absence of or decrease in body movement

arm, back, or jaw pain

black, tarry stools

bladder pain

bleeding after defecation

bleeding gums

blood in the urine or stools

blurred vision

body aches or pain

burning while urinating

burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings

chest pain or discomfort

chest tightness or heaviness

chills

cold sweats

colds

confusion

convulsions

cough or hoarseness

decreased urine

diarrhea

difficult or labored breathing

difficult, burning, or painful urination

dilated neck veins

dizziness

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

dry mouth

ear congestion

extra heartbeats

fainting

fast, slow, irregular, pounding, or racing heartbeat or pulse

fever or chills

flu-like symptoms

frequent urge to urinate

frequent urination

general feeling of discomfort or illness

headache

headache, severe and throbbing

heart murmur

increased need to urinate

increased sweating

increased thirst

increased volume of pale, dilute urine

irregular breathing

itching, pain, redness, or swelling on the leg

joint pain, stiffness, or swelling

lightheadedness

loss of appetite

loss of voice

lower back, side, or stomach pain

muscle aches and pains

muscle cramps

nasal congestion

nausea or vomiting

nervousness

numbness or tingling in the hands, feet, or lips

pain or discomfort in the arms, jaw, back, or neck

pain, tension, and weakness upon walking that subsides during periods of rest

partial or slight paralysis

passing urine more often

pinpoint red or purple spots on the skin

pounding in the ears

runny nose

shakiness in the legs, arms, hands, or feet

shivering

sneezing

sore on the leg

sore throat

sudden decrease in the amount of urine

sweating

swelling

swelling of the face, fingers, feet, or lower legs

tightness in the chest

trembling or shaking of the hands or feet

trouble sleeping

troubled breathing

uncomfortable swelling around the anus

unusual bleeding or bruising

unusual tiredness or weakness

vomiting of blood or material that looks like coffee grounds

weakness

weight gain

Rare

Bluish-colored lips, fingernails, or palms

dark urine

pale skin

rapid heart rate

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

disturbed color perception

double vision

feeling of constant movement of self or surroundings

halos around lights

headache, severe and throbbing

loss of consciousness

night blindness

overbright appearance of lights

paralysis

sensation of spinning

tunnel vision

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

Acid or sour stomach

anxiety

back pain

belching

blemishes on the skin

bloated

breast pain

burning feeling in the chest or stomach

burning, dry, or itching eyes

change in color vision

changes in vision

cold sweats

congestion

constipation

continuing ringing or buzzing or other unexplained noise in the ears

cough producing mucus

decreased interest in sexual intercourse

difficulty seeing at night

difficulty with moving

discharge, excessive tearing

double vision

drooping upper eyelids

dull ache or feeling of pressure or heaviness in the legs

earache

excess air or gas in the stomach or intestines

feeling of constant movement of self or surroundings

feeling of warmth

feeling unusually cold

frequent urge to defecate

frozen shoulder

full feeling

hearing loss

heartburn

hyperventilation

inability to have or keep an erection

increased appetite

increased sensitivity of the eyes to sunlight

increased sputum

indigestion

irritability

itching skin near damaged veins

lack or loss of strength

loss in sexual ability, desire, drive, or performance

muscle or bone pain

muscle stiffness or weakness

nightmares

noisy breathing

pain or tenderness around the eyes and cheekbones

passing gas

pimples

poor concentration

rash

redness of the face, neck, arms, and occasionally, upper chest

redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid

redness, swelling, or soreness of the tongue

restlessness

seeing double

sensation of spinning

sleepiness or unusual drowsiness

small clicking, bubbling, or rattling sounds in the lung when listening with a stethoscope

small lumps under the skin

sore mouth or tongue

stiff neck

stomach bloating, burning, cramping, or pain

stomach discomfort or upset

straining while passing stool

stuffy nose

sudden sweating

swollen feet and ankles

tender, swollen glands in the neck

tenderness in the stomach area

terrifying dreams causing sleep disturbances

tooth disorder

trouble swallowing

uncontrolled twisting movements of the neck

voice changes

weight loss

white patches in the mouth, tongue, or throat

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 riociguat (Adempas®), sildenafil (Viagra®), tadalafil (Cialis®), or vardenafil (Levitra®) while you are using this medicine. Using these medicines together may lower your blood pressure and 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.

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.