Nitroglycerin (GTN): uses, side effects & brands

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

Nitroglycerin is a fast-acting nitrate spray/tablet for sudden angina. 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

Relieving a sudden angina attack
Preventing angina before exertion
Heart failure or high blood pressure in hospital (injection)

Common brand names

India: Angispray, Nitrocontin, GTN
Worldwide: Nitrostat, Nitro-Dur

Common side effects

Headache
Dizziness or light-headedness
Flushing
Fast heartbeat

Before taking it — precautions

Sit down before using it, as it can make you faint
Never use with erectile-dysfunction medicines like sildenafil or tadalafil
Tell your doctor about low blood pressure, anaemia or recent head injury

When to see a doctor urgently

Chest pain that does not ease after repeat doses as advised (call emergency services)
Fainting or collapse
Severe headache with vomiting

Not a prescription — no dose shown. The right dose of nitroglycerin 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

How quickly does GTN work?

Spray or tablet under the tongue usually works within a few minutes.

What if the pain does not go away?

Follow your doctor's instructions; if pain is not relieved, call an ambulance as it may be a heart attack.

Does GTN expire quickly?

Tablets can lose strength once opened; check the expiry and replace as advised. Sprays last longer.

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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.