Glyceryl trinitrate is used to relieve sudden attacks of angina (chest pain which occurs when the heart does not receive enough blood supply). This medicine also helps prevent chest pain before you engage in activities that can trigger chest pain.
This medicine cannot cure your chest pain; it can only temporarily relieve your discomfort. If your doctor has given you other heart medicines, make sure you take them as directed.
Take Glyceryl trinitrate exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
This medicine is available as a sublingual tablet and spray.
Take or use this medicine while you are sitting.
If you are taking the sublingual tablet, do not swallow, chew or crush the tablet. It must be placed under your tongue until it dissolves.
If you are using the spray, follow these steps:
- If you are using the spray for the first time, remove the cap and press the pump a few times until you produce a fine mist.
- Hold the spray upright and place the spray outlet close to your mouth.
- Press down the pump button firmly and release the spray directing it under your tongue.
- Release the pump button and close your mouth immediately after each dose. Hold your breath for a moment to avoid breathing in the spray. Avoid swallowing and do not spit out or rinse your mouth for 5-10 minutes after using this medicine.
- Replace the cap.
The dose of this medicine will be decided by your doctor. Your doctor will advise you on the course of treatment depending on the severity of your condition and your response to the medication.
Alert your doctor if you have the following conditions:
- hypertrophic obstructive cardiomyopathy (abnormally thick heart muscle that results in blockage of blood flow)
- increased pressure in the brain e.g. head trauma or injury, bleeding in the brain
- severe anaemia (low red blood cell count in the body)
- constrictive pericarditis (inflammation of the sac-like membrane surrounding the heart)
- pericardial tamponade (a condition where fluid builds up in the sac around the heart that prevents it from pumping enough blood)
- acute circulatory failure (a serious sudden condition when the heart and blood vessels cannot supply enough oxygen-rich blood to the organs and tissues)
- severe low blood pressure
- low volume of circulating fluids in the body which have not been treated
- narrowing of the heart valves
as Glyceryl trinitrate may not be suitable for you.
Do not take Glyceryl trinitrate with medicines used to treat impotence and certain medicine used to treat high blood pressure in the lungs. Please see the section "Can I take this with other medicines?" below for more information.
Inform your doctor if you have the following conditions:
- hypothyroidism (underactive thyroid gland)
- disease of the blood vessels supplying the brain
- lung problem
- recent history of heart attack
- nutrient imbalance due to insufficient or excessive dietary intake
- low body temperature
- low levels of oxygen in the blood
- severe liver disease
- severe kidney disease
Let your doctor know if you are pregnant or breastfeeding.
Be sure to check with your doctor or pharmacist before giving Glyceryl trinitrate to the elderly. Elderly people may be more sensitive to the side effects.
Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
Glyceryl trinitrate may cause dizziness. If affected, do not drive or take part in any activity in which you need to be alert.
This medicine may cause your blood pressure to fall suddenly when you get up from a sitting or lying down position and you may feel giddy. To minimise this problem, stand up slowly.
Other side effects include any of the following: headache, dizziness with sensations of spinning, generalised weakness or lack of energy, drowsiness, nausea, vomiting, and flushing.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- severe dizziness, passing out
- worsening of chest pain, fast heartbeat
- bluish skin, shortness of breath, tiredness
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Do not take Glyceryl trinitrate with the following medicines:
- medicines used to treat impotence e.g. sildenafil, vardenafil, tadalafil
- riociguat (medicine used to treat high blood pressure in the blood vessels leading to the lungs)
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines for high blood pressure e.g. amlodipine, captopril
- medicines to treat depression e.g. amitriptyline
- medicines for migraine (severe throbbing pain or pulsating sensation usually affecting one side of the head that is often accompanied by nausea, vomiting, and sensitivity to light and sound) e.g. ergotamine
- heparin (blood-thinning medicine)
- acetylcysteine (medicine used to treat lung disorders associated with abnormal, thick, and viscous mucus secretions [phlegm])
This list does not include all medicines that may interact with Glyceryl trinitrate.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements, and medicines that you buy without a prescription.
Avoid alcohol. Alcohol intake may worsen the side effects caused by Glyceryl trinitrate.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.
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