Patient information from BMJ

Unstable angina: what is it?

Last published:Apr 08, 2025

Unstable angina is a medical emergency. It's a severe pain in your chest that can be a warning sign of a heart attack. There are treatments for unstable angina, so if it happens it's important to go to hospital straight away.

In this patient information, we talk about the causes and symptoms of unstable angina. To learn more about treatments, see the leaflet Unstable angina: what are the treatment options? 

What is unstable angina?

Unstable angina is a pain in your chest that happens if your heart is not getting enough oxygen. This pain:

• might come on suddenly

• might get worse over a short period

• is not caused by physical activity or is different to the type of pain usually caused by physical activity

• doesn't get better with rest or painkillers

• is a warning sign of a heart attack.

You might not have had chest pain before. Or you might have had a type of chest pain called stable angina. Stable angina usually happens when you are more active than usual. For example walking up a hill. It can also be caused by emotional stress. Stable angina usually only lasts a few minutes. For some people resting is enough to make it stop, but others also need to take their angina medicine.

But unstable angina can happen any time, even when you are resting. And it might not go away when you take you angina medicine.

If you get unstable angina it is an emergency. You should call the emergency services and get immediate medical help.

Most people get unstable angina because they have a blood clot in an artery in their heart. This is usually caused by a build up of fat in the lining of the arteries.

If the blood clot completely blocks the artery and no oxygen gets to your heart muscle, it's called a heart attack. This can permanently damage your heart.

What are the symptoms of unstable angina?

The main symptom of unstable angina is severe pain in your chest. But it can come on in different ways. 

Often, prolonged pain is the main symptom. Sometimes it might be a worsening of stable angina pain or a severe new pain.

The pain of unstable angina can feel as if there's a weight on your chest or like a squeezing, crushing, or gripping sensation. It usually lasts at least 20 minutes.

The feeling is usually in the middle of the chest. But you might get it

• in your neck and jaw, or in your back

• down one or both of your arms, making them feel heavy

• as stomach pain or as if you have indigestion.

Sometimes people get other symptoms, such as:

• breathlessness and sweating

• nausea

• dizziness or fainting

• weakness.

If you have unstable angina you should go to hospital for emergency treatment. At hospital they will do tests to check on your heart. These tests will probably include an electrocardiogram (ECG) to see how your heart is beating, and blood tests. These will help doctors to tell whether you have unstable angina or are having a heart attack.

What happens next?

If you've had an attack of unstable angina, you might feel anxious. You may worry about having a heart attack. But most people recover well. With the right treatment many people with unstable angina can keep doing the things they enjoy.

There may be lifestyle changes you can make to help improve your heart health, and reduce your chances of a heart attack. For example, it will be important to control your blood pressure. You should take any blood pressure medicines prescribed by your doctor. If you have diabetes you will need to be extra careful about managing your blood sugar levels. Stopping smoking and keeping your weight within a healthy range is also important.

For more about living with angina see our patient information on: Unstable angina: what are the treatment options?, Stable angina: what is it?, and Stable angina: what are the treatment options?

Having angina might make you worry more, or make you feel down. This can affect your quality of life. If your mood is very low or you feel depressed, talk to your doctor. There are treatments that can help.

There are many charities and support groups to help people with heart conditions. You could ask your doctor for a list of local organisations, or try searching online.