The nuclear stress test can show how blood flows through your heart muscles. This reveals how well the heart pumps blood and areas of your heart muscles that do not get enough blood.

Nuclear stress is an imaging test that shows how well blood flows into your heart when you’re exercising or at rest. This test is also known as myocardial perfusion imaging (MPI) or a thallium stress test.

This test is considered noninvasive, meaning it happens outside the body. It uses a small amount of a radioactive substance called a tracer, or radionuclide, that is injected into your veins.

Doctors perform nuclear stress tests for different reasons, such as to:

  • find out whether a person‘s heart is healthy enough to manage physical activities
  • check whether a person has had a heart attack or has other heart conditions, as well as whether there is damage from the condition
  • to find out why a person is experiencing chest pain or other discomforts

Let’s discuss nuclear stress tests, how long they take to perform, and how to prepare for them.

The duration of nuclear stress tests varies but typically takes about 3 to 4 hours. Here is an overview of the steps that healthcare professionals perform during the test.


As you are resting, a medical professional will insert an intravenous (IV) line into a vein in your arm and inject the radioactive substance through it. Thallium is one of the most commonly used radioactive tracers.

The tracer will enter your bloodstream, and the dye will reveal the movement of blood through your body. It will then get absorbed in the heart within about 15 to 40 minutes.

At-rest scan

As you continue resting, usually lying on an X-ray table, a gamma camera scans your heart for small amounts of gamma radiation that the tracer emits and takes pictures.

This takes about 10 to 30 minutes.


You may be asked to exercise to increase your heart rate. A medical professional will place blood pressure cuffs on your arm and electrodes on your chest to monitor your heart. They will have you increase the intensity and speed of your exercise until you reach a target heart rate. The exercise phase can take about 10 to 15 minutes, according to MedlinePlus.

If you are unable to exercise, you may be asked to use a medication to induce stress similar to that of exercise for about 10 to 20 minutes, per MedlinePlus.

Post-exercise injection

After the exercise, you will receive another radioactive tracer injection and wait for another 15 to 40 minutes for your heart to absorb the radioactive tracer.

Post-exercise scan

The professional performing your test may ask you to return to the X-ray table, where they will take pictures of your heart. They will monitor you for about 10 to 15 minutes until your heart rate returns to usual.

Here are things your doctor may advise you to do before the test:

  • Do not eat certain foods after midnight on the night before your test to prevent you from getting sick during the test.
  • Do not eat anything, but drink only water for about 4 to 6 hours before the test, according to the American Heart Association (AHA).
  • Avoid beverages like coffee, tea, and soda about 24 hours before your test, the AHA advises.
  • If you smoke, avoid smoking or taking tobacco products about 8 hours before the test, per the AHA.
  • Bring loose-fitting clothes and comfortable shoes for the exercise session.

A nuclear stress test usually does not cause significant pain during the procedure. However, you will feel a pinch from the needle during the IV line insertion. Also, the tracer may feel cold as it initially flows into the vein in your arm.

Your experience with the procedure may vary depending on whether a medication was used to achieve stress and the type of medication used.

Often, you can return to your usual activities after a nuclear stress test. But because the test requires an exercise session, some people may feel headaches, a racing heart, or dizziness after the test.

Some people may also experience shortness of breath and chest pain. If you do experience these symptoms during or after the test, tell your doctor right away.

Here are answers to some common questions people ask about nuclear stress tests.

Is a nuclear stress test painful?

A nuclear stress test is usually not painful. But some people may experience headaches, nausea, or dizziness after the test.

How long are you radioactive after a nuclear stress test?

Depending on the type of radioactive tracer used, it may take a few hours to some days for it to leave your body through urine.

Can you drive after nuclear stress test?

Some people may be able to drive after a nuclear stress test. But it may be safer to bring someone with you who can drive you back after the test.

What should I avoid after a nuclear stress test?

Some people give off small amounts of radiation after a nuclear test. So, it will be best to avoid young children and babies after the test. Also, if you’re breastfeeding or chestfeeding, speak with your doctor about safety precautions.

When will I get the results of a nuclear stress test?

It may take a few days for your healthcare team to process your test results, after which they will give you an appointment to discuss it with you.

A nuclear stress test is a noninvasive test used to show blood flow through the heart muscle during exercise and at rest. The test takes about 3 to 4 hours and usually doesn‘t cause serious complications. While this test is useful for diagnosing certain heart conditions, it may not be ideal for pregnant people.