Ismo Side Effects

Generic Name: isosorbide mononitrate

Note: This page contains information about the side effects of isosorbide mononitrate. Some of the dosage forms included on this document may not apply to the brand name Ismo.

Not all side effects for Ismo may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to isosorbide mononitrate: oral tablet, oral tablet extended release

In addition to its needed effects, some unwanted effects may be caused by isosorbide mononitrate (the active ingredient contained in Ismo). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking isosorbide mononitrate:

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
  • Bluish-colored lips, fingernails, or palms
  • dark urine
  • pale skin
  • rapid heart rate

If any of the following symptoms of overdose occur while taking isosorbide mononitrate, get emergency help immediately:

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 of the side effects that can occur with isosorbide mononitrate may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

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

For Healthcare Professionals

Applies to isosorbide mononitrate: oral tablet, oral tablet extended release


Isosorbide mononitrate (the active ingredient contained in Ismo) is generally well-tolerated.[Ref]

Nervous system

Nitrate-induced headaches are probably due to vasodilation, and may resolve spontaneously over days to weeks or respond to acetaminophen analgesia.[Ref]

Nervous system side effects such as headache have occurred in up to 36% of patients. In a large multicenter trial, 1.2% of patients discontinued therapy due to headache. Up to 8% of patients experienced dizziness/vertigo symptoms.[Ref]


Organic nitrates may induce a sudden drop in systemic blood pressure and enhanced vagal tone, resulting in possible inhibition of reflex tachycardia and syncope.[Ref]

Cardiovascular side effects include flushing, increased heart rate, hypotension, and orthostasis. These are more likely in patients with hypovolemia or who are on antihypertensive medications. Syncope has been reported in rare cases. Due to tolerance to the antianginal effects of the drug, eccentric dosing is usually recommended. This typically means giving the drug upon wakening and again approximately seven hours later, leaving a "nitrate-free" period during the night to decrease the incidence of tolerance.[Ref]


Gastrointestinal side effects are relatively uncommon, and include nausea and constipation in 1% to 3% of patients.[Ref]


Hypersensitivity reactions, presenting as pruritus and drug rash, are reported with the organic nitrates.[Ref]


Nitrates converted to nitrites may accelerate the oxidation of hemoglobin, resulting in abnormally high plasma concentrations of methemoglobin. While most cases of methemoglobinemia are asymptomatic, methemoglobin levels greater than 60% usually induce symptoms, particularly in the presence of underlying coronary artery disease. Treatment in symptomatic persons is methylene blue 1% solution 2 mg/kg intravenously over 10 minutes. It is recommended that affected patients be screened for NADP-methemoglobin reductase deficiency.[Ref]

A rare hematologic side effect of nitrates is methemoglobinemia.[Ref]


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3. Thadani U, Maranda CR, Amsterdam E, Spaccavento L, Friedman RG, Chernoff R, Zellner S, Gorwit J, Hinderaker PH "Lack of pharmacologic tolerance and rebound angina pectoris during twice-daily therapy with isosorbide-5-mononitrate." Ann Intern Med 120 (1994): 353-9

4. Kosoglou T, Patrick JE, Cohen A, Radwanski E, Christopher DC, Affrime MB "Pharmacokinetics of isosorbide-5-mononitrate after oral administration of an extended release mononitrate formulation versus a standard dinitrate formulation." Clin Ther 17 (1995): 241-51

5. Heepe W, Gathmann-Lewik U "Antianginal efficacy and tolerability of 50 mg sustained-release isosorbide 5-mononitrate in an open twelve-month observation study." Cardiology 74 (1987): 34-9

6. Emanuelsson H, Ake H, Kristi M, Arina R "Effects of diltiazem and isosorbide-5-mononitrate, alone and in combination, on patients with stable angina pectoris." Eur J Clin Pharmacol 36 (1989): 561-6

7. Uberbacher HJ, Steinorth G, Glocke M, Abshagen U "An open, long-term, multi-centre study of the anti-anginal efficacy and safety of isosorbide 5-mononitrate at low doses in patients with coronary heart disease." Pharmatherapeutica 3 (1983): 331-41

8. Kanto JH "Oral isosorbide-5-mononitrate: pharmacokinetics and clinical efficacy." Int J Clin Pharmacol Ther Toxicol 25 (1987): 129-35

9. Brun J "Patient compliance with once-daily and 5-isosorbide mononitrate: a comparative study." J Int Med Res 22 (1994): 266-72,350

10. Sporl-Radun S, Betzien G, Kaufmann B, Liede V, Abshagen U "Effects and pharmacokinetics of isosorbide dinitrate in normal man." Eur J Clin Pharmacol 18 (1980): 237-44

11. May K, Eghbal B, Ahmadinejad M, Ensslin HD, Weiss M "Evaluation of effectiveness and tolerability of isosorbide mononitrate during a three-year period in patients with angina pectoris." Cardiology 79 (1991): 46-50

12. Parker JO "Eccentric dosing with isosorbide-5-mononitrate in angina pectoris." Am J Cardiol 72 (1993): 871-6

13. Chrysant SG, Glasser SP, Bittar N, Shahidi FE, Danisa K, Ibrahim R, Watts LE, Garutti RJ, Ferraresi R, Casareto R "Efficacy and safety of extended-release isosorbide-mononitrate for stable effort angina pectoris." Am J Cardiol 72 (1993): 1249-56

14. "Product Information. ISMO (isosorbide mononitrate)." Wyeth-Ayerst Laboratories, Philadelphia, PA.

15. Gibson GR, Hunter JB, Raabe DS, Jr Manjoney DL, Ittleman FP "Methemoglobinemia produced by high-dose intravenous nitroglycerin." Ann Intern Med 96 (1982): 615-6

16. Robicsek F "Acute methemoglobinemia during cardiopulmonary bypass caused by intravenous nitroglycerin infusion." J Thorac Cardiovasc Surg 90 (1985): 931-4

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