While nuclear stress tests are considered safe, there are some precautions that need to be followed both during and after the test.

If you or a doctor suspects you might have an undiagnosed heart condition, one diagnostic tool that could be used is a nuclear stress test.

During this test, you’ll be injected with a radioactive chemical called a tracer. A technician will use a specialized camera to take pictures of the tracer as it’s absorbed by your heart tissue. This will be done while you’re at rest and then again with your heart rate elevated.

Doctors can use these results to find evidence of a previous heart attack or to diagnose conditions like coronary artery disease.

Let’s take a detailed look at precautions you should take during and after the test.

Before the test, let the doctor know what medications — including over-the-counter (OTC) supplements and herbal remedies — you’re currently taking. Also mention any known allergies.

Follow all instructions regarding food, liquid, and medication restrictions leading up to the test.

During the test, if you feel unusual in any way, let the technician or doctor know what it is you’re feeling.

Should older people get a nuclear stress test?

There are no specific risks for older adults getting a nuclear stress test. The level of stress you experience will be determined by your age, health, and ability level.

Who should avoid getting a nuclear stress test?

A nuclear stress test should be avoided for people who are or might be pregnant. If there’s a possibility you’re pregnant, let the doctor know before getting a nuclear stress test.

If you’re nursing, you can have a nuclear stress test, but still let the doctor know. You’ll need to follow special instructions after the test before resuming nursing.

After the test, the doctor will give you specific instructions about what you may and may not do. These will vary based on the specific radioactive tracer you were given and the amount used.

While the radiation exposure of this test is considered safe, your body may remain slightly radioactive for a period of hours to days. You can help to flush your body of radioactivity by drinking plenty of water.

You may want to take a shower and then wash your hands regularly. You’ll be advised to avoid contact with children and babies for a period of hours or days.

If you’re nursing, you’ll need to throw away one or several feedings’ worth of milk or freeze them until they become safe. A doctor can provide detailed instructions specific to your test.

Most people can resume normal daily activities immediately after the test. Depending on your test results, the doctor might advise you to limit certain types of physical activity or avoid certain foods or medications.

Side effects of nuclear stress tests are usually mild, and may include:

More serious side effects are rare but could include an allergic reaction to the radioactive tracer.

The two types of radioactive tracers most commonly used are thallium-201 (Tl-201) and technetium-99 (Tc-99).

Th-201 decays more slowly than Tc-99. The amount of Th-201 goes down by half every 3 days, while Tc-99 goes down by half every 6 hours.

At the same time, your body is constantly filtering out these chemicals and removing them through your urine and stool.

The tracer will usually be gone from your body within 1 or 2 days.

Nuclear stress test radiation risk to others

The risk to others is low, but it’s not zero. For this reason, you should avoid close contact with children and babies for 1 to 2 days after the test. Frequent handwashing will also help prevent the spread of radioactive particles.

Nuclear stress tests have minimal symptoms and side effects associated with them.

Stress is usually brought on through exercise, but medications can also be used to cause stress. When stress is caused chemically with medication, there tend to be more side effects, but they’re usually still mild and short-lasting.

If your symptoms get worse after the test instead of better, call a doctor.

Medical emergency

Go to the nearest emergency room or call 911 or local emergency medical services if you experience chest pain or difficulty breathing. This may be a symptom of a more serious reaction.

Abnormal results could indicate several things, including heart damage or heart disease.

If blood flow is blocked in some parts of your heart, you may need to avoid certain activities, foods, or medications. You might start taking new medications, or in some cases, you might require surgery.

Depending on the results, the doctor might want to perform additional diagnostic tests like cardiac catheterization.

Here are some of the most common questions people have about recovering from a nuclear stress test:

How much radiation do you emit after a nuclear stress test?

Most people are exposed to about 3 millisieverts of radiation over the course of a year. During a nuclear stress test, you can expect to be exposed to somewhere between 3 and 22 millisieverts of radiation, depending on the tracer used.

This is usually limited to your own body, and you’re only minimally radioactive for a period of 1 to 2 days after the test.

What should I avoid after a nuclear stress test?

Avoid close contact with children, babies, and people who are pregnant for 1 to 2 days after the test. Follow the doctor’s guidance on any restrictions related to food, medication, or exercise.

Can I drink coffee after a nuclear stress test?

Some people can drink coffee after a nuclear stress test, but others might need to avoid caffeine, which can include coffee, tea, chocolate, and other foods and beverages. Ask the doctor if you can have caffeine and how soon.

Why am I so tired after a nuclear stress test?

After exerting your cardiovascular system, you may feel tired. You can expect to feel back to your normal level of restfulness after a night’s sleep.

Nuclear stress tests involve having a radioactive tracer injected into your bloodstream. The tracer will decay on its own over time, and your body will also remove it through your urine and stool.

A doctor will give you specific instructions as to what foods, medications, and activities you should avoid both before and after the test.

For 1 to 2 days after the test, you’ll want to avoid children, babies, and pregnant people, and you should wash your hands regularly.