Isosorbide Dinitrate

Medication Information Leaflet

What is this medication for?

Isosorbide Dinitrate (ISDN) belongs to a class of medications called Nitrates. Nitrates are used to prevent and treat the symptoms of angina (chest pain). Angina is caused by lack of blood supply and oxygen to your heart. Nitrates work by relaxing blood vessels so that more blood and oxygen is supplied to the heart.

When you take this medication regularly on a long-term basis, it can help to treat angina by reducing the number of heart attacks that occur.

Nitrates can also be used with other medications for the treatment of heart failure, a condition where the heart is weak and is unable to pump enough blood to the rest of the body.

How should I take/use this medication?

  • Do not stop taking your medication without checking with your healthcare professional. Stopping your medication suddenly may cause angina attacks. Ask your doctor for recommendations on how to reduce the dose slowly before stopping completely.
  • This medication should be taken before food, on an empty stomach.
  • This medication is used to reduce the number of angina attacks that occur. They should not be used for immediate relief for chest pain.

What should I do if I forget to take/use this medication?

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for your next dose, take only the usual dose. Do not double your dose or use extra medication to make up for the missed dose. 

What precautions should I take?

Inform your healthcare professional if: 
  • You are allergic to this medication or any of the other ingredients of this medication
  • You are pregnant, planning to become pregnant, or breastfeeding 

What are some common side-effects of this medication?

Side effects may include:
  • Dizziness, lightheadedness or faintness
    • This may occur especially when you get up quickly from lying or sitting down. Getting up slowly or changing posture slowly may help. Take a rest by sitting or lying down if you feel dizzy.
    • This is also more likely to happen if you drink alcohol, stand for a long period of time, exercise or when the weather is hot. Do limit the amount of alcohol you drink while you are on Nitrates. Do take extra care during exercise, when the weather is hot or if you need to stand for long periods of time.
  • Temporary headache
    • This is a common side effect that will go away after taking the medication for a while. You may choose to take painkillers such as Paracetamol at the start of using Nitrates, to relieve the temporary headaches. Consult your healthcare professional if the headaches do not go away or become worse.
  • Flushing or redness of the skin
  • Fast heartbeat 
  • Nausea and Vomiting 

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 
  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body
If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take this medication?

Do not take Sildenafil (Viagra®), Tadalafil (Cialis®), Vardenafil (Levitra®) if you are taking this medication. When Sildenafil, Tadalafil or Vardenafil is taken with Nitrates, your blood pressure can lower greatly, resulting in dizziness, lightheadedness or fainting. In some cases, death has been reported when Sildenafil was taken with Nitrates.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. Throw away all expired medications. 

How should I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on July 2019

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