What Not to Do Before a Pulmonary Function Test

Small mistakes before your test can affect your results

If you’ve been scheduled for a pulmonary function test, you’re already taking an important step toward understanding your lung health. These tests provide valuable insight into how well your lungs are working and help guide diagnosis and treatment for a wide range of respiratory conditions.

What many patients don’t realize is that what you do before your test can directly impact the accuracy of your results.

At The Respire Institute, we want to make sure your test reflects your true baseline lung function. That means avoiding a few common habits in the hours leading up to your appointment.

Why preparation matters

Pulmonary function tests measure airflow, lung capacity, and how efficiently your lungs exchange oxygen. These results are used to diagnose conditions such as asthma, COPD, and interstitial lung disease, as well as to monitor how well treatments are working.

If your lungs are temporarily affected by outside factors like food, medication, or physical activity, the results may not accurately represent your typical lung function.

According to the American Thoracic Society, proper preparation helps ensure that pulmonary testing produces reliable and clinically meaningful data.

Avoid heavy meals before your test

Eating a large meal right before your appointment can make it harder for your lungs to fully expand.

A full stomach presses upward against the diaphragm, which can limit how deeply you are able to inhale. This may result in lower lung volume readings during the test.

It is best to eat a light meal if needed and avoid anything heavy within a few hours of testing.

Do not smoke before testing

Smoking can temporarily irritate and constrict the airways, which may affect airflow measurements.

Even a single cigarette before your test can lead to inaccurate results and may make it more difficult to interpret your lung function correctly.

If you smoke, you will typically be asked to avoid smoking for several hours prior to your appointment.

Be cautious with inhalers and medications

Certain inhalers and bronchodilator medications can change how your lungs perform during the test.

Depending on the reason for your evaluation, your provider may ask you to temporarily pause specific medications before testing. This allows your care team to understand your baseline lung function without the influence of medication.

It is important to follow your provider’s instructions carefully and not stop any medications unless directed to do so.

Avoid strenuous exercise beforehand

Exercise can temporarily increase your breathing rate and alter how your lungs respond during testing.

While regular physical activity is important for overall health, it is best to avoid vigorous exercise immediately before your pulmonary function test so that your lungs are in a resting state.

This helps ensure that the results reflect your typical breathing patterns.

Wear comfortable clothing

Pulmonary function testing requires you to take deep breaths and exhale forcefully. Tight clothing around your chest or abdomen can restrict your ability to breathe fully.

Wearing loose, comfortable clothing allows you to perform the test more effectively and helps ensure accurate measurements.

Arrive prepared and relaxed

It’s normal to feel unsure about what to expect, but pulmonary function testing is safe, non-invasive, and guided by trained professionals.

You will be coached through each step, and the test is designed to be straightforward and manageable for patients of all ages.

Arriving on time and relaxed helps the testing process go smoothly and ensures that you are able to perform the breathing maneuvers correctly.

Setting yourself up for accurate results

Pulmonary function testing plays a key role in diagnosing and managing respiratory conditions. By following simple preparation guidelines, you help your care team gather the most accurate information possible.

In the context of Rest to Reset, this is about establishing a clear baseline. When we understand exactly how your lungs are functioning, we can build a treatment plan that supports better breathing, improved endurance, and long-term health.

Ready for your pulmonary evaluation?

If you have questions about your upcoming test or need guidance on preparation, our team at The Respire Institute is here to help.

Accurate testing leads to better answers — and better answers lead to better care.