Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Imdur
  2. Imdur ER
  3. Ismo
  4. Monoket


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.

This product is available in the following dosage forms:

  • Tablet, Extended Release
  • Tablet

Before Using

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.


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.

Drug Interactions

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

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.


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

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

  1. Abnormal heart sound
  2. absence of or decrease in body movement
  3. arm, back, or jaw pain
  4. black, tarry stools
  5. bladder pain
  6. bleeding after defecation
  7. bleeding gums
  8. blood in the urine or stools
  9. blurred vision
  10. body aches or pain
  11. burning while urinating
  12. burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  13. chest pain or discomfort
  14. chest tightness or heaviness
  15. chills
  16. cold sweats
  17. colds
  18. confusion
  19. convulsions
  20. cough or hoarseness
  21. decreased urine
  22. diarrhea
  23. difficult or labored breathing
  24. difficult, burning, or painful urination
  25. dilated neck veins
  26. dizziness
  27. dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  28. dry mouth
  29. ear congestion
  30. extra heartbeats
  31. fainting
  32. fast, slow, irregular, pounding, or racing heartbeat or pulse
  33. fever or chills
  34. flu-like symptoms
  35. frequent urge to urinate
  36. frequent urination
  37. general feeling of discomfort or illness
  38. headache
  39. headache, severe and throbbing
  40. heart murmur
  41. increased need to urinate
  42. increased sweating
  43. increased thirst
  44. increased volume of pale, dilute urine
  45. irregular breathing
  46. itching, pain, redness, or swelling on the leg
  47. joint pain, stiffness, or swelling
  48. lightheadedness
  49. loss of appetite
  50. loss of voice
  51. lower back, side, or stomach pain
  52. muscle aches and pains
  53. muscle cramps
  54. nasal congestion
  55. nausea or vomiting
  56. nervousness
  57. numbness or tingling in the hands, feet, or lips
  58. pain or discomfort in the arms, jaw, back, or neck
  59. pain, tension, and weakness upon walking that subsides during periods of rest
  60. partial or slight paralysis
  61. passing urine more often
  62. pinpoint red or purple spots on the skin
  63. pounding in the ears
  64. runny nose
  65. shakiness in the legs, arms, hands, or feet
  66. shivering
  67. sneezing
  68. sore on the leg
  69. sore throat
  70. sudden decrease in the amount of urine
  71. sweating
  72. swelling
  73. swelling of the face, fingers, feet, or lower legs
  74. tightness in the chest
  75. trembling or shaking of the hands or feet
  76. trouble sleeping
  77. troubled breathing
  78. uncomfortable swelling around the anus
  79. unusual bleeding or bruising
  80. unusual tiredness or weakness
  81. vomiting of blood or material that looks like coffee grounds
  82. weakness
  83. weight gain


  1. Bluish-colored lips, fingernails, or palms
  2. dark urine
  3. pale skin
  4. rapid heart rate

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

Symptoms of overdose

  1. Blurred or loss of vision
  2. bulging soft spot on the head of an infant
  3. change in consciousness
  4. change in the ability to see colors, especially blue or yellow
  5. cold, clammy skin
  6. disturbed color perception
  7. double vision
  8. feeling of constant movement of self or surroundings
  9. halos around lights
  10. headache, severe and throbbing
  11. loss of consciousness
  12. night blindness
  13. overbright appearance of lights
  14. paralysis
  15. sensation of spinning
  16. 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

  1. Acid or sour stomach
  2. anxiety
  3. back pain
  4. belching
  5. blemishes on the skin
  6. bloated
  7. breast pain
  8. burning feeling in the chest or stomach
  9. burning, dry, or itching eyes
  10. change in color vision
  11. changes in vision
  12. cold sweats
  13. congestion
  14. constipation
  15. continuing ringing or buzzing or other unexplained noise in the ears
  16. cough producing mucus
  17. decreased interest in sexual intercourse
  18. difficulty seeing at night
  19. difficulty with moving
  20. discharge, excessive tearing
  21. double vision
  22. drooping upper eyelids
  23. dull ache or feeling of pressure or heaviness in the legs
  24. earache
  25. excess air or gas in the stomach or intestines
  26. feeling of constant movement of self or surroundings
  27. feeling of warmth
  28. feeling unusually cold
  29. frequent urge to defecate
  30. frozen shoulder
  31. full feeling
  32. hearing loss
  33. heartburn
  34. hyperventilation
  35. inability to have or keep an erection
  36. increased appetite
  37. increased sensitivity of the eyes to sunlight
  38. increased sputum
  39. indigestion
  40. irritability
  41. itching skin near damaged veins
  42. lack or loss of strength
  43. loss in sexual ability, desire, drive, or performance
  44. muscle or bone pain
  45. muscle stiffness or weakness
  46. nightmares
  47. noisy breathing
  48. pain or tenderness around the eyes and cheekbones
  49. passing gas
  50. pimples
  51. poor concentration
  52. rash
  53. redness of the face, neck, arms, and occasionally, upper chest
  54. redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
  55. redness, swelling, or soreness of the tongue
  56. restlessness
  57. seeing double
  58. sensation of spinning
  59. sleepiness or unusual drowsiness
  60. small clicking, bubbling, or rattling sounds in the lung when listening with a stethoscope
  61. small lumps under the skin
  62. sore mouth or tongue
  63. stiff neck
  64. stomach bloating, burning, cramping, or pain
  65. stomach discomfort or upset
  66. straining while passing stool
  67. stuffy nose
  68. sudden sweating
  69. swollen feet and ankles
  70. tender, swollen glands in the neck
  71. tenderness in the stomach area
  72. terrifying dreams causing sleep disturbances
  73. tooth disorder
  74. trouble swallowing
  75. uncontrolled twisting movements of the neck
  76. voice changes
  77. weight loss
  78. 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.