Isosorbide mononitrate (Oral route)


eye-soe-SOR-bide mon-oh-NYE-trate

Brand Names:

  • Imdur
  • Imdur ER
  • Ismo
  • Monoket

Dosage Forms:

  • Tablet, Extended Release
  • Tablet






Uses of This Medicine:

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.

Before Using This Medicine:

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:


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.


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

Older adults—

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


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.

Other 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.

  • Avanafil
  • Riociguat
  • Sildenafil
  • Tadalafil
  • Vardenafil

Other interactions—

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. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

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:

  • Allergy to nitrates (eg, amyl nitrate, butyl nitrate) and nitrites—Should not be used in patients with these conditions.
  • Congestive heart failure or
  • Heart attack, recent or
  • Hypertrophic cardiomyopathy (a heart disease) or
  • Hypotension (low blood pressure) or
  • Hypovolemia (low amount of blood)—Use with caution. May make these conditions worse.

Proper Use of This Medicine:

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.


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.

  • For prevention of angina:
    • For oral dosage form (extended-release tablets):
      • Adults—At first, 30 or 60 milligrams (mg) once a day. Take the dose in the morning right after you wake up. Your doctor may increase your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults—20 milligrams (mg) two times a day. Take the first dose in the morning right after you wake up, and the second dose 7 hours later.
      • Children—Use and dose must be determined by your doctor.

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.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

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.

Precautions While Using This Medicine:

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.

Side Effects of This Medicine:

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
cold sweats
cough or hoarseness
decreased urine
difficult or labored breathing
difficult, burning, or painful urination
dilated neck veins
dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
dry mouth
ear congestion
extra heartbeats
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, 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
loss of appetite
loss of voice
lower back, side, or stomach pain
muscle aches and pains
muscle cramps
nasal congestion
nausea or vomiting
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
sore on the leg
sore throat
sudden decrease in the amount of urine
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
weight gain
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
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
back pain
blemishes on the skin
breast pain
burning feeling in the chest or stomach
burning, dry, or itching eyes
change in color vision
changes in vision
cold sweats
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
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
inability to have or keep an erection
increased appetite
increased sensitivity of the eyes to sunlight
increased sputum
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
noisy breathing
pain or tenderness around the eyes and cheekbones
passing gas
poor concentration
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
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.

Last Updated: 6/10/2021
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