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Nitrates

Nitrates are medications given to treat patients with angina. They are available in different forms and can work as both a treatment and preventative measure for the condition.  

  1. Treat angina.
  2. Available in three types and various forms.
  3. Manage pain and prevent it from occurring.

If you have any concerns about angina or its symptoms, you can speak with one of our GPhC-registered clinicians via our online video consultation service. They are available for appointments between 9.30am-4.30pm, Monday to Friday.

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Product information

What are nitrates?

Nitrates are drugs that are given to treat angina. They are available in three different forms: glyceryl trinitrate (GTN), isosorbide dinitrate and isosorbide mononitrate. While these drugs do not cure the underlying causes of angina, they can manage its symptoms effectively by relaxing the blood vessels of the heart, widening them in order to allow blood to flow more freely.

What is angina? 

Angina is a pain in the chest that is caused by a decrease in blood flow to the heart. While not a life-threatening condition in itself, it can be a sign that you are at risk of something more serious, including heart attacks and strokes. 

There are two forms of the condition: stable and unstable. Stable angina is the most common type of angina, and occurs during stressful moments, whether physical or psychological. It tends to subside when you are resting. Unstable angina can occur without warning, and seemingly without reason, and does not subside when you are resting. It’s more serious than stable angina and requires careful monitoring.

What symptoms can angina cause?

Symptoms of angina can vary in severity and frequency. The main symptom is a chest pain that spreads to the neck, jaw and back and is often described as heavy, tight and dull. In some cases (usually amongst women) these pains can be described as sharp. Other symptoms include nausea, loss of breath, fatigue and discomfort similar to indigestion. 

If you experience any of these symptoms and have never been diagnosed with the condition, you should seek immediate medical attention as it may be a sign of something more serious. In cases where you have already been diagnosed, you should wait and see if the symptoms pass. If after five minutes, and having taken nitrate medication, the symptoms have not subsided, you should seek medical help immediately.

How is angina diagnosed?

Diagnosing angina is not always straightforward, and several tests may be needed to determine if you have the condition or not. Diagnosis usually consists of talking to your GP about your symptoms, what you were doing when they were triggered and if you have a family history of heart issues. Your prescribing clinician may also ask you about your lifestyle, including if you smoke and your dietary habits. Calculating your body mass index (BMI) and taking a blood pressure test will likely be required, as will conducting blood tests to measure your cholesterol levels. 

Following tests from your GP, you may need to make a hospital appointment for further examination, including an electrocardiogram (ECG), which may be taken during exercise, usually on a treadmill or exercise bike. Another test that may be carried out is a coronary angiograph, which is a scan that requires an injection of dye.

How is angina treated?

Medication for angina is available in two forms, although other medications to reduce the risk of heart attacks and strokes may also be required. Stable angina will likely be treated with medications to treat symptoms when they occur. GTN is typically used, and is available as either a mouth spray or tablet that can be dissolved under the tongue. It can also be used as a preventative measure if you are looking to take exercise that may trigger an attack. 

An alternative to GTN is isosorbide dinitrate, which essentially works in the same way but may be more suitable for some people. There is also isosorbide mononitrate, which is used as a preventative measure. These medications are more likely to be prescribed for severe symptoms and symptoms associated with unstable angina. However, the most common treatments for unstable angina are beta blockers and calcium channel blockers, as well as blood thinning medications to lower the risk of blood clots. 

If medications are not an effective treatment, surgery may be considered as a last resort. In terms of procedures, there are two options. A coronary artery bypass grafts (CABGs) involves taking a blood vessel from another part of your body and attaching it to the coronary artery above and below the narrowed region or blockage. 

The second option is a percutaneous coronary intervention (PCI), which uses a stent to widen the narrowed artery, allowing blood to flow more freely. Each procedure is thought to be as effective as the other, and your specific circumstances usually determine which is the best option for you. 

If you would like to discuss nitrates or any related conditions with one of our registered clinicians, they are available from 9.30am-4.30pm, five days a week, via our online video consultation service. They can also provide fit notes and referrals to specialists for treatment, where suitable.  

Page last reviewed:  17/07/2020
Side effects and warnings

What side effects can nitrates cause? 

Side effects are always a risk with any medication, so it is important to understand what these are before you start treatment. Your prescribing doctor can discuss any potential side effects for your treatment with you. You can also refer to the patient information leaflet that comes with your medication. 

The following information relates to glyceryl trinitrate tablets, and may not be relevant for your specific treatment. If you experience any of the following symptoms you should seek immediate medical attention: worsening of angina symptoms, chest pains, difficulty breathing, increased rate of breathing, headaches, tiredness, blue colouring of the lips, fingers or toes, rapid heartbeat, slowed heartbeat, blindness in one eye, weakness in one arm or leg, weakness in one entire side of the body, difficulty speaking, slurred speech, loss of coordination, loss of consciousness and allergic skin reactions.

Other side effects include: 

Very common (may affect more than 1 in 10 people): throbbing headache.

Common (may affect up to 1 in 10 people): spinning sensation, a fall in blood pressure, dizziness, drowsiness and a lack of energy. 

Uncommon (may affect up to 1 in 100 people): fainting, facial flushing, nausea, vomiting, burning sensations, tongue blistering and circulatory collapse. 

Very rare (may affect up to 1 in 10,000 people): restlessness, heartburn, bad breath and itchy, flaky or red skin.

The following symptoms have been reported but there is not enough data to establish their frequency: pain around the eye, changes in vision, palpitations and weakness.

Can nitrates cause interactions with other medications?

You should make your prescribing clinician aware of any medications and supplements you are taking before starting treatment with nitrates. This is to ensure that your prescription is safe for you.

It’s particularly important that you inform your doctor if you are taking any of the following: sildenafil, tadalafil, vardenafil, heparin, n-acetylcysteine (used to treat paracetamol overdose), other nitrate medications, nitrates, high blood pressure treatments, medicines that can cause dry mouth, apomorphine and ergot alkaloids.

Warnings and precautions when taking nitrates 

In the case of glyceryl trinitrates, you should avoid using them if you: are allergic to glyceryl trinitrate or other nitrate medications; are anaemic; have raised pressure in your head; have bleeding on the brain; have painful eyes; have changes in vision; have bad headaches, glaucoma or hypertrophic obstructive cardiomyopathy.

Your doctor may decide that this treatment is not suitable for you if you have: severe liver issues; kidney problems; an underactive thyroid; had a recent heart attack; low body temperature; an unbalanced diet; digestion problems; low levels of oxygen in the blood; low blood pressure; low blood volume; conditions that lower blood volume in the heart; narrowing heart valves; inflammation of the heart; build up of fluid around the heart; heart failure; a disease of the blood vessels supplying the brain.

What types of nitrates are available? 

There are three types of nitrates available: glyceryl trinitrates and isosorbide dinitrates (to treat symptoms as they occur) and isosorbide mononitrates (which prevent attacks from occurring). They also come in various forms, which are often designed for specific circumstances. For example, a GTN tablet that dissolves on the tongue when attacks occur. Other forms include tablets, sprays, ointments, patches, extended release tablets and capsules. 

Are nitrates safe to use if you are pregnant?

It’s essential that you tell your prescribing clinician if you are pregnant, think you may be pregnant, are planning on becoming pregnant or are breastfeeding before starting treatment.

Page last reviewed:  17/07/2020
Questions and Answers

Is it safe to drink alcohol whilst taking nitrates? 

You should avoid drinking alcohol whilst taking nitrates as it can impact on their effectiveness on the body.

Can nitrates cause any allergic reactions?  

You should make your prescribing clinician aware of any allergies that you have so that they can prescribe the most suitable treatment for you. 

Nitrate tablets can contain lactose, which some people have an intolerance of. Your prescribing clinician may take this into account when determining the best medication for you.

Can I buy nitrates over the counter? 

No. Nitrates are available on prescription only.  

How can I buy nitrates online? 

Our GMC-registered clinicians can discuss nitrates and any related conditions with you via our online video consultation service. You can make an appointment to speak with one of them between 9.30am-4.30pm, Monday to Friday. They can also provide referrals to specialists for treatment and fit notes, where appropriate. 

Page last reviewed:  17/07/2020

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