Stable Angina vs. Unstable Angina: What's the Difference?

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Man with chest pain

Chest pain is called “angina” and can occur any time blood flow to the heart muscle becomes restricted. Sometimes, angina happens in a predictable pattern, such as when you’re exercising. Other times, angina occurs without warning or for no apparent reason. Knowing which type of angina you or a loved one is experiencing can help get emergency medical attention when needed.

Stable Angina vs. Unstable Angina

When angina occurs predictably, it is called “stable angina.” This means you can reasonably predict that certain situations—such as exercising—will trigger chest pain. Stable angina is the most common type and usually can be treated by resting and taking a medication like nitroglycerin.

Sometimes, though, angina strikes without warning or for no apparent reason, even when you’re resting. This unpredictable type of angina is called “unstable angina” and is the more serious type of angina because it can indicate you’re going to have a heart attack. Medications and rest usually do not make unstable angina go away.

Unstable angina is sometimes called “acute coronary syndrome,” though heart attack itself also falls under this description. Acute coronary syndrome is a term for any group of diseases or conditions that can suddenly stop or restrict blood flow to the heart.

Unstable Angina Symptoms

The difference between stable angina and unstable angina lies partly in when the symptoms occur. Both types of angina cause chest pain or pressure, but the symptoms of unstable angina can occur when:

  • You’re resting.
  • You don’t feel stressed.

In addition, unstable angina usually comes on suddenly and gets worse rapidly over the course of 15 to 20 minutes. Other symptoms of unstable angina include:

  • Chest pain that does not get better by taking nitroglycerin
  • Drop in blood pressure that occurs with the chest pain

Unstable angina occurs more often in men than in women. Some of the other risk factors for unstable angina include:

  • Abnormal cholesterol levels
  • Sedentary lifestyle

If you have been diagnosed with stable angina, you should follow your doctor’s instructions regarding what to do when you develop chest pain.

Anyone who develops sudden chest pain or pressure for no known reason—whether you’ve been diagnosed with unstable angina or not—should seek emergency medical attention because these symptoms can indicate you’re about to have a heart attack. Be sure to tell emergency medical responders if you’ve been diagnosed with unstable angina so they can provide the best treatment for your symptoms.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Dec 1
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Angina. U.S. National Library of Medicine, MedlinePlus.
  2. Angina. American Academy of Family Physicians.
  3. Stable Angina. MedlinePlus, U.S. National Library of Medicine.
  4. Acute Coronary Syndrome. MedlinePlus, U.S. National Library of Medicine.
  5. Unstable Angina. MedlinePlus, U.S. National Library of Medicine.
  6. Unstable Angina. American Heart Association.

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