isosorbide mononitrate at a glance
Medicine class
Organic nitrate vasodilator and anti-anginal medicine.
Main licensed use
Prevention of angina attacks in adults.
Not for sudden attacks
Use the rapid-acting angina treatment prescribed for you instead.
Modified-release forms
Swallow whole with water; do not chew or crush.
What is isosorbide mononitrate used for?
Selected UK products are licensed for:
Preventing angina pectoris in adults.
How does isosorbide mononitrate work?
It relaxes blood vessels through nitric-oxide-related signalling. It mainly widens veins, reducing blood returning to the heart, and can also widen arteries. This lowers the heart’s workload and improves its oxygen balance.
isosorbide mononitrate preparations and strengths
Modified-release capsule
Route: Oral
Strengths: 25 mg, 50 mg
Modified-release tablet
Route: Oral
Strengths: 30 mg, 40 mg, 60 mg
How to take isosorbide mononitrate
Follow the instructions for the specific brand and formulation supplied.
Swallow tablets or capsules with water.
Do not chew or crush modified-release tablets or capsules.
They can generally be taken with or without food.
Whether a tablet can be divided is product-specific; check its leaflet or ask a pharmacist.
isosorbide mononitrate side effects
Common or expected effects
- Headache, especially after starting treatment
- Dizziness, weakness or tiredness
- Feeling sick
- Flushing
- Low blood pressure or light-headedness when standing
- Fast heartbeat
Get urgent medical advice
- Fainting or collapse
- Severe or symptomatic low blood pressure
- Markedly fast or slow heartbeat
- Severe eye pain with blurred or lost vision
- Severe allergic reaction, including facial or throat swelling or breathing difficulty
- Blue or grey skin or lips, which may indicate a serious blood-oxygen problem
isosorbide mononitrate in pregnancy
NHS guidance states that isosorbide mononitrate can be used during pregnancy but recommends prompt review by an obstetrician and cardiologist. Product information notes limited established pregnancy safety.
isosorbide mononitrate while breastfeeding
Breastfeeding may be possible when the infant is healthy, after discussion with a doctor or pharmacist. Transfer into milk has not been adequately quantified. Seek advice if the infant feeds poorly, gains weight unexpectedly slowly, is unusually sleepy or becomes irritable.
isosorbide mononitrate interactions
Important interactions include:
PDE-5 inhibitors, including sildenafil, tadalafil and vardenafil
Contraindicated because the combination can cause a profound, potentially life-threatening fall in blood pressure.
Riociguat
Contraindicated because combined vasodilation can cause severe hypotension.
Common questions about isosorbide mononitrate
Answers are fully visible for fast scanning and source review.
Will isosorbide mononitrate stop a sudden angina attack?
No. It works too slowly. Follow your prescribed angina action plan and use the rapid-acting medicine provided for attacks.
Can I take sildenafil or tadalafil with it?
No. PDE-5 inhibitors can cause a dangerous fall in blood pressure when combined with isosorbide mononitrate.
More questions about isosorbide mononitrate
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.