Glyceryl trinitrate (GTN)
Glyceryl trinitrate (GTN) relaxes blood vessels quickly. In the UK it is used under prescriber advice to treat or prevent angina chest pain due to reduced heart blood flow. Sprays under the tongue and sublingual tablets are common formats.
This medicine is part of the Blood pressure, cholesterol & related category.
Generic name: glyceryl trinitrate
Quick answers
Short replies to searches people often run before speaking to a clinician. For the overview of what the medicine is used for, see the short summary under the page title above.
What is it for?
Glyceryl trinitrate (GTN) relaxes blood vessels quickly.
How long does it take to work?
Blood pressure can fall over days to weeks after starting or changing dose; attend follow-up checks your GP arranges.
What are common side effects?
Throbbing headache, flushing, dizziness, or light-headedness are common and often lessen after repeated use.
Can you take paracetamol or ibuprofen with it?
Ask your GP or pharmacist before taking Glyceryl trinitrate (GTN) with paracetamol or ibuprofen. Many adults use paracetamol for short periods when appropriate; NSAIDs such as ibuprofen need extra checks with your other medicines and health conditions.
More about what Glyceryl trinitrate (GTN) is used for
Glyceryl trinitrate (GTN) relaxes blood vessels quickly. In the UK it is used under prescriber advice to treat or prevent angina chest pain due to reduced heart blood flow.
Sprays under the tongue and sublingual tablets are common formats.
How does Glyceryl trinitrate (GTN) work, and how long does it take to work?
It releases nitric oxide–like effects on vessels, improving blood supply to the heart muscle within minutes.
It does not cure narrowed arteries; it relieves symptoms while longer-term prevention uses other medicines and lifestyle measures.
How and when should you take Glyceryl trinitrate (GTN)?
At angina: sit down, use the spray or tablet under the tongue as your pharmacist trained you, and repeat after a few minutes if pain persists per your action plan.
Check expiry dates — out-of-date GTN may not work. Replace opened bottles within the timeframe on the label.
What are the common side effects of Glyceryl trinitrate (GTN)?
Throbbing headache, flushing, dizziness, or light-headedness are common and often lessen after repeated use.
Low blood pressure can occur — rise slowly after dosing.
Serious side effects of Glyceryl trinitrate (GTN) — when to get urgent help
If chest pain does not ease after rest and repeated doses as per your plan, or you have crushing pain with breathlessness, sweat, or radiation to arm or jaw, call 999 — it could be a heart attack.
Fainting with GTN needs urgent review.
What if you miss a dose of Glyceryl trinitrate (GTN)?
GTN is often used as needed rather than a fixed daily schedule — carry it as advised. Preventer plans for angina are separate.
Who should not take Glyceryl trinitrate (GTN)?
Recent use of Sildenafil, Tadalafil, or vardenafil for erectile dysfunction can cause dangerous blood pressure drops with nitrates — always tell prescribers.
Severe anaemia, raised pressure inside the skull, and some heart conditions need specialist advice before use.
Can you take paracetamol or ibuprofen with Glyceryl trinitrate (GTN)? — other interactions
PDE5 inhibitors are a major interaction. Other blood pressure drugs add to hypotension.
Glyceryl trinitrate (GTN) in pregnancy and breastfeeding
Use only if clearly needed in pregnancy; discuss with your prescriber.
Blood tests and monitoring on Glyceryl trinitrate (GTN)
Your cardiology or GP team reviews angina frequency and may adjust beta-blockers, statins, or procedures alongside GTN.
What might your GP prescribe instead of Glyceryl trinitrate (GTN)?
Isosorbide mononitrate is a longer-acting nitrate sometimes used for prevention — different timing rules apply.
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Reviewed by UK registered pharmacists for accuracy and clarity. Content is informational only.
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Frequently asked questions about Glyceryl trinitrate (GTN)
People also ask — common Google searches
- What is Glyceryl trinitrate (GTN) used for?
- Glyceryl trinitrate (GTN) relaxes blood vessels quickly. In the UK it is used under prescriber advice to treat or prevent angina chest pain due to reduced heart blood flow. Sprays under the tongue and sublingual tablets are common formats.
- How long does Glyceryl trinitrate (GTN) take to work?
- Blood pressure can fall over days to weeks after starting or changing dose; attend follow-up checks your GP arranges. Always follow your prescriber’s follow-up plan.
- Can you take Glyceryl trinitrate (GTN) with paracetamol or ibuprofen?
- Ask your GP or pharmacist before taking Glyceryl trinitrate (GTN) with Paracetamol or Ibuprofen. Many adults use paracetamol for short periods when appropriate; NSAIDs such as ibuprofen need extra checks with your other medicines and health conditions.
- What are the side effects of Glyceryl trinitrate (GTN)?
- Throbbing headache, flushing, dizziness, or light-headedness are common and often lessen after repeated use. Low blood pressure can occur — rise slowly after dosing. See the sections below for more detail, including serious side effects and when to seek urgent help.
- How many GTN sprays can I use?
- Follow the emergency plan your clinician gave you — often one or two doses a few minutes apart, then emergency services if pain continues. If you are unsure, ask your GP or cardiac nurse to write it down.
- Why does GTN give a headache?
- Vessel dilation in the head causes headache in many people. It often improves over time; severe or new headache patterns should still be mentioned to your doctor.
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