Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Isosorbide Mononitrate Tablets 40 mg
⚠ This medicine appears to have been discontinued
The electronic medicines compendium (emc) no longer publishes a Summary of Product Characteristics for this product, which usually means it is no longer marketed in the UK. The patient leaflet below is kept for reference, but the product may not be available.
If you were prescribed this medicine, other products containing Isosorbide mononitrate may still be available. Do not stop your treatment — ask your pharmacist or GP what to use instead.
What it is and what it is used for
for Isosorbide Mononitrate Tablets belong to a group of medicines called nitrate vasodilators. These work by relaxing the blood vessels of the heart, reducing the strain on the heart making it easier to pump blood. Isosorbide Mononitrate Tablets are used to prevent angina pectoris. Angina usually feels like a tight pain in the chest, neck or arm area. The pain comes from the heart muscle and is a sign that part of it is not getting enough oxygen for the amount of work it is doing.
What you need to know before you take it
e Isosorbide Mononitrate Tablets Do not take Isosorbide Mononitrate Tablets if:
- you are allergic (hypersensitive) to isosorbide mononitrate, isosorbide dinitrate or any of the other ingredients of Isosorbide Mononitrate Tablets (see section 6). An allergic reaction may include a rash, itching or difficulty breathing
- you have severe anaemia (reduction in red blood cells which can make the skin pale and cause weakness or breathlessness)
- you are having a heart attack (myocardial infarction)
- you have ever had a stroke
- you have a low blood volume (hypovolaemia), very low blood pressure
- your blood has stopped circulating around your body properly (circulation failure)
- you take sildenafil, tadalafil and vardenafil or any other phosphodiesterase inhibitor (used for male impotence). See the section "Other medicines and Isosorbide Mononitrate Tablets"
- you are also taking riociguat. See the section "Other medicines and Isosorbide Mononitrate Tablets"
- you are suffering from "shock" or vascular collapse
- you have an eye disease called glaucoma (increased pressure in the eye)
- you have been diagnosed with any of the following heart conditions: hypertrophic obstructive cardiomyopathy (HOCM), constrictive pericarditis, cardiac tamponade, low cardiac filling pressures, aortic/mitral valve stenosis
- you have diseases associated with raised head pressure e.g. brain haemorrhage (bleeding); head injury (trauma) Do not take Isosorbide Mononitrate Tablets if any of the above applies to you. If you are not sure, talk to your doctor or pharmacist before taking Isosorbide Mononitrate Tablets. Warnings and precautions Talk to your doctor or pharmacist before taking Isosorbide Mononitrate Tablets if you:
- have an underactive thyroid gland
- are undernourished as a result of a poor diet
- have severe liver or kidney problems
- suffer from hypothermia (very low body temperature)
- suffer from very poor circulation
- had any serious damage to your heart, such as a heart attack
- have an eye disease called glaucoma (increased pressure in the eye) Do not take Isosorbide Mononitrate Tablets if any of the above applies to you. If you are not sure, talk to your doctor or pharmacist before taking Isosorbide Mononitrate Tablets. Other medicines and Isosorbide Mononitrate Tablets: Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This includes medicines that you buy without a prescription and herbal medicines. This is because Isosorbide Mononitrate Tablets can affect the way some medicines work and some medicines can have an effect on Isosorbide Mononitrate Tablets. Do not take Isosorbide Mononitrate Tablets if you are taking the following medicines:
- Sildenafil, tadalafil and vardenafil used to treat male erection dysfunction, should not be taken if taking nitrate preparations such as Isosorbide Mononitrate Tablets because a severe and possibly dangerous fall in blood pressure can occur. This would result in collapse, unconsciousness and could be fatal. You must not stop taking Isosorbide Mononitrate Tablets to take sildenafil, tadalafil or vardenafil as this will increase your chances of having an angina attack.
- Riociguat since this can cause hypotension (abnormally low blood pressure)
- Noradrenalin (norepinephrine) to treat sharp and severe drop in blood pressure
- Acetylcholine used in some operations
- Medicines to treat high blood pressure such as ACE inhibitors, beta blockers, alpha blockers, angiotensin-II receptor agonists, clonidine, diazoxide, diuretics (water tablets), methyldopa, moxonidine
- Histamine (used mostly as a diagnostic agent in some medical conditions)
- Tricyclic antidepressants (used to treat depression) and neuroleptics (used to treat anxiety)
- Dihydorergotamine used for migraine Do not take Isosorbide Mononitrate Tablets if any of the above applies to you. If you are not sure, talk to your doctor or pharmacist before taking Isosorbide Mononitrate Tablets. Isosorbide Mononitrate Tablets and alcohol: Do not drink alcohol. It could increase the effect of Isosorbide Mononitrate Tablets and lower your blood pressure too much. If this happens, you may feel dizzy or faint. Pregnancy, breast-feeding and fertility: If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Driving and using machines: Isosorbide Mononitrate Tablets may give you headache, blurred vision or make you feel dizzy or tired, make sure you are not affected before you drive or operate machinery.
Isosorbide Mononitrate Tablets contains lactose: If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicinal product.
How to take it
Isosorbide Mononitrate Tablets Always take this medicine exactly as described in this leaflet or as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure. Taking this medicine
- Take the tablets with a drink of water.
- Isosorbide Mononitrate Tablets 20 mg and 40 mg can be divided into equal doses. How much to take Adults
- The initial dose recommended, for patients not already accustomed to nitrate therapy to prevent angina pectoris, is one tablet twice a day.
- The usual adult dose is 20 mg tablet two or three times a day, then a maintenance dose of between 20-120 mg a day.
- You will need to have a period of time (usually when you are sleeping) when no tablets are taken. This is called a "nitrate low" period and is needed to make sure your medicine remains effective. You must not take Isosorbide Mononitrate Tablets for a sudden attack of angina. If you have a sudden attack, take a glyceryl trinitrate tablet (follow the instructions given on the label). Patients with kidney or liver disease: A lower dose may be given. Elderly: Dose should be reduced especially in patients with kidney or liver disease. Children: Do not give these tablets to children. If you take more Isosorbide Mononitrate Tablets than you should: If you take more Isosorbide Mononitrate tablets than you should, take to a doctor or go to a hospital straight away. Take the medicine pack with you so the tablets can be identified. Signs of an overdose: pulsing headache, over excited, flushing, feeling or being sick, cold sweats, sweating, feeling dizzy or spinning sensation, restlessness, warm flushed skin, blurred vision fainting or passing out, fast heart beat or fall in blood pressure. Increase pressure in the brain with confusion and neurological deficits can sometimes occur. Methaemoglobinaemia, which manifests in symptoms such as bluish discoloration of the skin and mucous membranes (cyanosis); respiratory depression; seizures; irregular heart rate or rhythm. If you forget to take Isosorbide Mononitrate Tablets
- If you forget a dose, take it as soon as you remember it. However, if it is nearly time for the next dose, skip the missed dose.
- Do not take a double dose to make up for a forgotten dose. If you stop taking Isosorbide Mononitrate Tablets: Do not stop taking Isosorbide Mononitrate Tablets without first talking to your doctor. You should keep taking your medicine until your doctor tells you to stop. Do not stop taking it just because you feel better. If you stop taking the tablets your condition may get worse. If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them. The following side effects may happen with this medicine:
- Headaches
- Feeling sick (nausea)
- Feeling dizzy The above problems usually disappear with time. Other possible side effects: Seek immediate medical help if you have any of the following symptoms:
- Fainting or collapse
- Allergic reaction- skin rash, swelling of the skin of the extremities or face, swelling of lips, tongue or the mucous membranes in mouth, throat or airways resulting in shortness of breath or difficulty to swallow Very common side effects (may affect up to 1 in 10 people):
- Mild headaches at the start of treatment. Usually they get better after 1-3 weeks of treatment. Common side effects (may affect up to 1 in 10 people):
- Headache
- Dizziness
- Low blood pressure and/or light-headed on standing up
- Tiredness, drowsiness, feeling weak
- Fast or slow heart rate • Flushing They may occur for the first few days of treatment or after your dosage has been increased. Uncommon side effects (may affect up to 1 in 100 people):
- Fainting or collapse
- Feeling sick or being sick (nausea and/or vomiting), diarrhoea
- Skin rashes, looking pale
- Excessive sweating
- Restlessness • Worse angina Rare (may affect up to 1 in 1,000 people):
- Rash • Itchy skin
- Fainting Very rare side effects (may affect up to 1 in 10,000 people):
- Heartburn
- Red or scaly skin (exfoliative dermatitis) • Muscular pain (myalgia) Reporting of side effects: If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
How to store it
Isosorbide Mononitrate Tablets
- Keep this medicine out of the sight and reach of children.
- Do not use this medicine after the expiry date which is stated on the carton. The expiry date refers to the last day of that month.
- Store in a dry place, below 25°C.
- Do not throw away any medicine via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help to protect the environment. 6. Content of the pack and further information What Isosorbide Mononitrate Tablets contain: The active substance is isosorbide mononitrate. Each tablet contains either 10mg, 20mg or 40mg of the active substance. The other ingredients are lactose monohydrate, compressible sugar, sodium starch glycollate, magnesium stearate and colloidal silicon dioxide. What Isosorbide Mononitrate Tablets look like and content of the pack Isosorbide Mononitrate Tablets 10mg are white round tablets with an embossment "IM 10" on one side. Isosorbide Mononitrate Tablets 20mg/40mg are white round tablets, scored on one side with an embossment "ISMN 20"/"ISMN40". Pack sizes are 28, 50, 56, 60, 100 or 500 tablets. Not all pack sizes may be marketed. Marketing Authorisation Holder and Manufacturer: Dexcel® – Pharma Ltd., 2nd Floor, Bourn, 1 Manor House Drive, Coventry, CV1 2FX, UK This leaflet was last revised in June 2026. 1239741111-L
Frequently asked questions about Isosorbide Mononitrate Tablets 40 mg
How do I take Isosorbide Mononitrate Tablets 40 mg?
Isosorbide Mononitrate Tablets 40 mg comes as tablet containing 40mg. Always follow the dose your doctor or pharmacist has given you, and read the leaflet that comes with the medicine.
What is the active substance in Isosorbide Mononitrate Tablets 40 mg?
The active substance in Isosorbide Mononitrate Tablets 40 mg is isosorbide mononitrate.
Are there equivalent medicines to Isosorbide Mononitrate Tablets 40 mg?
Medicines with the same active substance, strength and form include: ISMO Retard, 40 mg, prolonged-release tablets, Isotard 40 mg XL Tablets, Isosorbide Mononitrate 40 mg Tablet. In total there are 4 equivalent products. They are interchangeable only if your prescriber or pharmacist says so.
Where does this information come from?
This leaflet reproduces the patient information leaflet approved for Isosorbide Mononitrate Tablets 40 mg, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.
Can I get Isosorbide Mononitrate Tablets 40 mg without a prescription?
Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.
About this leaflet
The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.
- Source: electronic medicines compendium (emc), Datapharm
- Active substance: isosorbide mononitrate
- Official document: view the original leaflet on emc →
⚕For healthcare professionals — Summary of Product Characteristics (SmPC)Full SmPC: dosage, interactions, contraindications, warnings+
4.1. Therapeutic indications
Isosorbide Mononitrate Tablets is indicated for the prophylaxis of angina pectoris.
4.2. Posology and method of administration
Posology
Dosage should be reduced in patients with renal or hepatic impairment.
Adults
One tablet to be taken asymmetrically (to allow a nitrate low period) two or three times a day. Patients already accustomed to prophylactic nitrate therapy may normally be transferred directly to a therapeutic dose of isosorbide mononitrate. For patients not already receiving prophylactic nitrate therapy it is recommended that the initial dose be one tablet of Isosorbide Mononitrate Tablets 20 mg twice a day.
The maintenance dose in individual patients is usually between 20- 120 mg daily.
The lowest effective dose should be used.
Elderly
No evidence of a need for routine dosage adjustment in older people has been found, but special care may be needed in those with increased susceptibility to hypotension or marked hepatic or renal insufficiency.
Children
The safety and efficacy of Isosorbide Mononitrate Tablets 40 mg has yet to be established in children.
Treatment with Isosorbide Mononitrate Tablets, as with any other nitrates, should not be stopped suddenly. Both the dosage and frequency should be tapered gradually (see section 4.4)
Method of administration
It is recommended that the tablets should be swallowed whole with a drink of water.
4.3. Contraindications
Isosorbide Mononitrate Tablets 40 mg should not be used in cases of acute myocardial infarction with low filling pressures, acute circulatory failure (shock, vascular collapse), or very low blood pressure, hypertrophic obstructive cardiomyopathy (HOCM), constrictive pericarditis, cardiac tamponade, low cardiac filling pressures, aortic/mitral valve stenosis and diseases associated with a raised intra-cranial pressure e.g. following a head trauma and including cerebral haemorrhage.
This product should not be given to patients with a known hypersensitivity to isosorbide dinitrate or mononitrate, to other nitrates or to any of the excipients
Isosorbide Mononitrate Tablets 40 mg should not be used in patients with marked anaemia, sever hypotension, closed angle glaucoma, toxic pulmonary oedema or hypovolaemia.
Phosphodiesterase Type 5 Inhibitors (e.g. sildenafil, tadalafil, vardenafil) have been shown to potentiate the hypotensive effects of nitrates and their co-administration with nitrates or nitric oxide donors is therefore contraindicated (see section 4.5).
Severe cerebrovascular insufficiency or hypotension are relative contraindications to the use of Isosorbide Mononitrate Tablets 40 mg.
Co-administration with riociguat (see section 4.5).
4.4. Special warnings and precautions for use
Isosorbide Mononitrate Tablets 40 mg should be used with caution in patients who have a recent history of myocardial infarction, or who are suffering from closed-angle glaucoma, hypothyroidism, hypothermia, malnutrition and sever liver or renal disease.
Symptoms of circulatory collapse may arise after first dose in patients with labile circulation and in patients already taking ACE inhibitors.
This product may give rise to postural hypotension and syncope in some patients. Severe postural hypotension with light headedness and dizziness is frequently observed after the consumption of alcohol, therefore alcohol should be avoided during treatment. Hypotension induced by nitrates may be accompanied by paradoxical bradycardia and increased angina.
In the event of an acute angina attack, sublingual treatment such as a GTN spray or tablet should be used instead of isosorbide mononitrate tablets.
Isosorbide Mononitrate Tablets contain sucrose and lactose and therefore patients with rare hereditary problems of galactose or fructose intolerance, total lactase deficiency, sucrase-isomaltase insufficiency glucose-galactose malabsorption should not take this medicine.
If the tablets are not taken as indicated (see section 4.2) tolerance to the medication and cross-tolerance to other nitrates may occur. The lowest effective dose should be used.
Treatment with isosorbide mononitrate tablets, as with any other nitrate, should not be stopped suddenly. Both the dosage and frequency should be tapered gradually (see section 4.2).
4.5. Interaction with other medicinal products and other forms of interaction
Isosorbide mononitrate can act as a physiological antagonist to noradrenaline, acetylcholine, histamine and other agents.
Concurrent administration of drugs with blood pressure lowering properties, e.g, beta-blockers, calcium channel blockers, vasodilators, alprostadil, aldesleukin, angiotensin II receptor antagonist, ACE inhibitors etc. may potentiate the hypotensive effect of Isosorbide Mononitrate Tablets. This may also occur with neuroleptics and tricyclic antidepressants.
Alcohol can accentuate cerebral ischaemia associated with postural hypotension.
Any blood pressure lowering effect of Isosorbide Mononitrate Tablets will be increased if used together with phosphodiesterase type 5 inhibitors (e.g. sildenafil, tadalafil and verdenafil) which are used for erectile dysfunction (see special warnings and contraindications). This might lead to life threatening cardiovascular complications. Patients who are on Isosorbide Mononitrate Tablets therapy therefore must not use phosphodiesterase type-5 inhibitors.
Reports suggest that concomitant administration of Isosorbide Mononitrate Tablets may increase the blood level of dihydroergotamine and its hypertensive effect.
The use of isosorbide mononitrate with riociguat, a stimulator of soluble guanylate cyclase, is contra-indicated (see section 4.3), since concomitant use can cause hypotension.
4.6. Fertility, pregnancy and lactation
The safety and efficacy of Isosorbide Mononitrate Tablets during pregnancy or lactation has not been established.
4.7. Effects on ability to drive and use machines
Dizziness, tiredness or blurred vision might occur at the start of treatment. The patients should therefore be advised that if affected, they should not drive or operate machinery. This effect may be increased by alcohol.
4.8. Undesirable effects
A very common (>10% of patients) adverse reaction to Isosorbide Mononitrate Tablets is throbbing headache. The incidence of headache diminishes gradually or disappears after 1-3 weeks and optimum dosage of isosorbide mononitrate may be achieved.
At the At the start of therapy or when the dosage is increased, hypotension and/or light headedness in the upright position are commonly observed (i.e in 1-10% of patients). These symptoms may be associated with cutaneous vasodilatation with flushing, dizziness, drowsiness, reflex tachycardia and occasionally unexplained bradycardia and a feeling of weakness.
Infrequently (i.e. in less than 1% of patients) nausea, vomiting, flushing and allergic skin reaction (e.g. rash) may occur sometimes severely. In single cases exfoliative dermatitis may occur.
Severe hypotensive responses have been reported for organic nitrates and include nausea, vomiting, restlessness, pallor and excessive perspiration. Uncommonly collapse may occur (sometimes accompanied by bradyarrhythmia and syncope). Uncommonly severe hypotension may lead to enhanced angina symptoms.
Very rarely (i.e. in less than 0.01%) myalgia may occur.
A few reports of heartburn most likely due to a nitrate induced sphincter relaxation have been recorded.
Tachycardia and paroxysmal bradycardia have been reported.
Nitrate-induced pituitary apoplexy has been reported in patients with undiagnosed pituitary tumours.
Reporting suspected adverse reactions
Reporting suspected adverse reactions after authorization of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medical product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme. Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
4.9. Overdose
Symptoms and signs:
Pulsing headache, hypotension, nausea, vomiting, flushing, cold perspiration, sweating, tachycardia, vertigo, restlessness, excitation, warm flushed skin, blurred vision and syncope. A rise in intracranial pressure with confusion and neurological deficits can sometimes occur. Methaemoglobinaemia (cyanosis, hypoxaemia, restlessness, respiratory depression, convulsions, cardiac arrhythmias, circulatory failure, raised intracranial pressure) occurs rarely.
Management:
Induction of emesis, consider oral activated charcoal if ingestion of a potentially toxic amount has occurred within 1 hour. Observe for at least 12 hours after the overdose. Monitor blood pressure and pulse. Correct hypotension by raising the foot of the bed and/or by expanding the intravascular volume. Other measures as indicated by the patient's clinical condition. If severe hypotension persists despite the above measures consider use of inotropes or intravenous administration of fluid.
If methaemoglobinaemia (symptoms or > 30% methaemoglobin), IV administration of methylene blue 1-2 mg/kg body weight. If therapy fails with second dose after 1 hour or contraindicated, consider red blood cell concentrates or exchange transfusion. In case of cerebral convulsions, diazepam or clonazepam IV, or if therapy fails, phenobarbital, phenytoin or propofol anaesthesia.
💬 Ask about this leaflet
Ask anything about Isosorbide Mononitrate Tablets 40 mg. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.
Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.
Medicines containing Isosorbide mononitrate
- Carmil XL 60 mg Tablets
- Chemydur 60XL Tablets
- Elantan LA 25 mg prolonged release capsules
- Elantan LA 50 mg prolonged release capsules
- Eumon 40 XL Modified Release Tablets (Isosorbide Mononitrate)
- Imdur Tablets 60mg
- ISMO 10, 10 mg, tablets
- ISMO 20, 20 mg, tablets
- ISMO Retard, 40 mg, prolonged-release tablets
- Isodur 25XL Capsules
- Isodur 50XL Capsules
- Isosorbide Mononitrate 10 mg Tablet
- Isosorbide Mononitrate 20 mg Tablet
- Isosorbide Mononitrate 40 mg Tablet