Preparing for Spirometry: What Smokers and Former Smokers Should Know Before a Lung Function Test

Preparing for Spirometry: What Smokers and Former Smokers Should Know

Spirometry is a simple breathing test that measures how much air your lungs hold and how fast you can blow it out, and it’s one of the most common tests ordered for smokers and former smokers. To prepare, avoid smoking, heavy exercise, alcohol, and large meals beforehand; bring a full medication list, and ask your provider whether to pause any inhalers first.

If you smoke or used to smoke, your provider may order spirometry to check for early airflow changes, monitor a diagnosed condition like COPD, or get a baseline before you start a new medication. Here is what to gather and confirm before you go.

1. A written list of every medication you take, including inhalers, with dose, frequency, and reason for taking it.
2. Confirmation from your care team about which inhalers to pause and when, since stopping the wrong medication too early or too late can skew results.
3. Loose, comfortable clothing that does not restrict a deep breath.
4. A note of your last cigarette, vape, or tobacco use, since same-day smoking can affect your readings.
5. Questions about what the results can and cannot tell you, written down so you don’t forget them in the moment.

What Is Spirometry, and Why Might It Be Ordered for a Smoker or Former Smoker?

Spirometry measures airflow by having you inhale deeply, then blow out as hard and fast as possible into a mouthpiece. Providers use it to help diagnose or monitor lung conditions such as asthma, COPD, and emphysema, and to assess lung function before certain treatments or surgeries.

For people with a smoking history, spirometry is often the first lung function test a provider orders, because it’s quick, low-risk, and gives a useful first look at airflow before anything more involved is needed. According to the National Heart, Lung, and Blood Institute (NHLBI), spirometry belongs to a broader family of pulmonary function tests that also includes lung volume testing, gas diffusion testing, and exercise-based tests, and a provider may order one or more of these depending on what your spirometry results suggest.

The test can also be repeated over time to track whether your lung function is stable, improving, or declining, and to see whether a medication is helping. It does not, on its own, diagnose a specific disease. Your provider combines the numbers with your symptoms, history, and sometimes imaging to reach a diagnosis.

If you are still smoking, a spirometry referral is not a judgment. It is a data point your care team can use, whether or not you are ready to quit. If you are thinking about quitting or want to understand your options, our guide to smoking and vaping cessation approaches covers that separately from this test.

What Should You Bring to a Spirometry Appointment, and What Medicines Might You Need to Pause?

Bring a complete medication list, including inhaler names, doses, and how often you use them, as well as any assistive devices you normally use. Ask your provider in advance whether you need to stop a bronchodilator before the test, because timing affects the accuracy of your results.

Certain inhaled medications — called bronchodilators — relax the airways temporarily, which can make your numbers look better than your day-to-day baseline. If your provider wants an accurate baseline reading, they may ask you to hold off on a bronchodilator for a set number of hours first. NHLBI’s patient preparation guidance lists general withholding windows by medication type, summarized below. These are general reference points, not personal medical instructions — your own provider’s directions always come first, and you should never stop a prescribed medication without checking with them.

A simple way to think about it, based on the same NHLBI guidance:

1. If you use a short-acting rescue inhaler like albuterol, plan to pause it for about 6 hours before your appointment, unless your provider says otherwise.
2. If you use a long-acting daily inhaler like salmeterol or formoterol, plan for a longer pause of about 24 hours, since it stays active in your system longer.
3. If you use an ultra-long-acting inhaler like tiotropium, ask specifically about the roughly 36-hour window, since these are the longest-acting and most likely to affect results if not paused correctly.
4. If you’re not sure which category your inhaler falls into, call your provider’s office before the appointment rather than guessing.

Beyond medications, NHLBI’s general patient preparation instructions also recommend arriving on time, wearing clothing that does not restrict a deep breath, avoiding a large meal within two hours of the test, avoiding heavy exercise for at least 30 minutes before, avoiding alcohol for at least four hours before, and not smoking on the day of the test. MedlinePlus adds that you should avoid caffeine before testing if your provider tells you to, and that you should keep dentures in if you normally wear them, since they help your lips seal tightly around the mouthpiece.

What Happens During the Test Itself?

During spirometry, a technician clips your nose shut, has you seal your lips around a mouthpiece, and asks you to take the deepest breath possible before blasting the air out as hard and fast as you can. You may repeat this several times, and sometimes again after inhaling a bronchodilator, to see if your airflow improves.

According to MedlinePlus, the basic sequence is the same across most spirometry visits: you sit in a chair with a soft nose clip on, breathe only through your mouth into the connected device, and follow the technician’s coaching on timing and effort. A standard spirometry test without a bronchodilator comparison typically takes about 15 minutes, while a test comparing results before and after an inhaled medication typically takes about 30 minutes, per the NHLBI.

The test itself carries very little physical risk. MedlinePlus notes that some people feel lightheaded, dizzy, or tired from the breathing effort, and coughing during or right after the test is common. If you feel unwell at any point, tell the technician — you can pause.

Effort matters more in this test than in most other lab work. A rushed or half-hearted breath can produce a misleadingly low reading, which is part of why technicians coach you closely and often ask for multiple attempts. If you are not sure you are doing a maneuver correctly, ask them to demonstrate it or explain it a different way.

What Do Spirometry Results Actually Show, and What Can’t They Tell You?

Spirometry results compare your breathing numbers to expected values for someone of your height, age, and sex, then show whether your airflow pattern looks obstructive, restrictive, or within a typical range. The test flags a pattern, not a specific disease, so your provider still needs your symptoms and history to reach a diagnosis.

Per MedlinePlus, an obstructive pattern means your airways are narrowed, making it harder for air to flow out — this is the pattern seen in conditions like asthma, chronic bronchitis, and emphysema. A restrictive pattern means your lungs cannot hold as much air as expected, which can happen with conditions such as pulmonary fibrosis or sarcoidosis, or when the chest wall cannot expand fully. Spirometry alone cannot pinpoint which specific disease is causing an abnormal pattern; that usually requires additional tests, imaging, or a specialist evaluation.

It is worth being direct about the limits here: a “normal” spirometry result does not rule out every lung problem, and an abnormal one does not automatically mean disease is present or progressing. Testing conditions, effort, and technique all affect the numbers. This is exactly why the same test may be repeated on a different day, or paired with other tools — such as a lung volume test, which measures total lung capacity, or a diffusion capacity test, which checks how well oxygen moves from your lungs into your blood — before your provider draws conclusions.

What Should You Ask at Your Follow-Up Appointment?

At your follow-up, ask what your specific numbers mean relative to the expected range for your height, age, and sex; whether the pattern is obstructive or restrictive; and what your provider recommends as a next step. If anything in your results surprised you, say so directly and ask for it to be explained again in plain language.

Useful follow-up questions include: Does anything here suggest a specific condition, or is more testing needed to know? Should this test be repeated on a schedule, and if so, how often? Would quitting smoking or reducing exposure to smoke change future results? Are there any home monitoring tools worth discussing, and how do they compare to what was measured in the office today? If you are curious about consumer devices like personal spirometers or peak flow meters, our overview of lung health monitoring devices explains how FDA-cleared medical devices differ from general wellness gadgets, which matters for how much weight to give a home reading.

If your results point toward COPD or another chronic respiratory concern, it is reasonable to ask your provider what monitoring or management looks like going forward. Our COPD and respiratory wellness section covers general educational background on living with reduced lung function, though it is not a substitute for care from your own pulmonology or primary care team. And if the conversation turns toward quitting, providers increasingly offer remote options; our telehealth smoking cessation hub explains how virtual prescribing for cessation medications generally works.

Does Your Smoking Status Change How the Test Is Done or Read?

You do not need to have quit smoking to get spirometry done, and you should not feel like you have to justify your smoking history to schedule it. That said, smoking on the day of the test can affect your readings, which is why same-day avoidance is part of standard preparation rather than a moral test.

If you are a former smoker, mention how long it has been since you quit and roughly how long and how much you smoked, since this history helps your provider interpret your results in context. There is no “too late” for spirometry to be useful, and there is no version of this test designed to shame you — it is a measurement tool, not a verdict.

Medical Disclaimer: This article is for general educational purposes only. It does not diagnose any condition, recommend treatment, or replace a conversation with your own licensed healthcare provider. Medication timing before spirometry should always follow your provider’s specific instructions, not general reference tables. If you have concerning symptoms such as severe shortness of breath, chest pain, or coughing up blood, seek emergency care. See our full medical disclaimer for more detail.

Frequently Asked Questions

Do I need to stop smoking before a spirometry test?

You should avoid smoking on the day of the test, since it can temporarily affect your airflow readings. You do not need to have quit long-term, and providers order this test for people at every stage of smoking or having quit. If you smoked shortly before your appointment, mention it — your provider can factor it into how they read your results.

How long does a spirometry appointment take?

A basic spirometry test without a bronchodilator comparison generally takes about 15 minutes, according to NHLBI. If your provider wants to compare your breathing before and after an inhaled medication, plan for closer to 30 minutes. Sitting and supine spirometry, done in both positions, can take about 30 minutes as well.

Will spirometry hurt or make me feel sick?

Spirometry does not hurt, but the deep, forceful breathing can leave some people feeling lightheaded, dizzy, or tired for a few minutes afterward, per MedlinePlus. Coughing during or right after the test is also common and not a sign that anything went wrong. Let the technician know if you feel unwell during the test.

Can spirometry alone diagnose COPD or asthma?

Spirometry shows whether your airflow pattern looks obstructive, restrictive, or typical, but it cannot name a specific disease on its own. Your provider combines the results with your symptoms, history, and sometimes additional tests, such as lung volume or diffusion capacity testing, to reach a diagnosis.

Should I bring my inhaler to the appointment?

Yes — bring your inhalers and a written list of every medication you take, even if your provider asked you to pause one beforehand. The technician needs to know exactly what you use and when your last dose was to interpret your results accurately. Having the actual inhaler on hand avoids any confusion about the exact medication name.