Isosorbide Mononitrate: uses, side effects & brands

Written & medically reviewed by Dr. Sanjay Anbu, MBBS · Last reviewed 5 November 2026

Isosorbide mononitrate is a nitrate that prevents angina by widening blood vessels. It belongs to the Heart medicine (angina, rhythm & failure) group. These support the heart in angina, heart failure and rhythm problems.

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Drug type — dosing is set by your doctor

Measure	Range
Drug class	Heart medicine (angina, rhythm & failure)
Type	Prescription
Dose	Individual — ask your doctor or pharmacist

What it is used for

Preventing angina attacks
Long-term angina control alongside other heart medicines
Heart failure (in some combinations, specialist use)

Common brand names

India: Monotrate, Ismo, Isordil (dinitrate)
Worldwide: Imdur, Monoket

Common side effects

Headache, especially at first
Dizziness on standing
Flushing
Fast heartbeat

Before taking it — precautions

Never take with erectile-dysfunction medicines like sildenafil or tadalafil (dangerous drop in blood pressure)
A daily nitrate-free gap is usually planned so it keeps working; follow your doctor's timing
Tell your doctor about low blood pressure, anaemia or recent head injury

When to see a doctor urgently

Chest pain that does not settle with rest or GTN (urgent)
Fainting or very low blood pressure
Severe or persistent headache

Not a prescription — no dose shown. The right dose of isosorbide mononitrate depends on age, weight, kidney/liver function and the condition, so MedDroid does not show a dose here. Always get your dose from a doctor or pharmacist and the leaflet inside the pack. General educational information only.

Frequently asked questions

Can isosorbide stop an angina attack?

No. It is for prevention. Use a fast-acting GTN spray or tablet for sudden attacks.

Why do I get headaches?

Nitrates widen blood vessels, including in the head. Headaches usually ease after the first weeks.

Why should I not take erection medicines?

Combining nitrates with these medicines can cause a dangerous fall in blood pressure.

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Sources & further reading

Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.