Spirometry (lung function test)

What is spirometry?

Spirometry is a breathing test that measures how much air you can blow out of your lungs and how quickly. You take a deep breath in and then blow out as hard and as fast as you can into a machine called a spirometer.

The two main measurements are the total amount of air you can force out (forced vital capacity, FVC) and how much you can blow out in the first second (forced expiratory volume in one second, FEV1). The pattern of these helps tell whether the airways are narrowed (as in asthma or COPD) or the lungs are restricted in some way.

Sometimes the test is repeated after you use a reliever inhaler to see whether your breathing improves. This 'reversibility' testing helps tell some conditions apart.

Spirometry measures how your lungs are working on the day; it does not by itself give a diagnosis. The result is interpreted alongside your symptoms, history and other tests, and it depends a lot on good technique and effort.

Types, options & approaches

There may be different ways to do this. The right approach depends on the clinical question and your circumstances.

Spirometry vs fuller lung function tests

Spirometry is often the first breathing test. If more detail is needed, it may be combined with lung volume and gas transfer tests.

Preparing for your test

• Follow any instructions about pausing inhalers beforehand — some relievers and preventers are stopped for a number of hours so reversibility can be assessed.
• Avoid smoking or vaping for at least a few hours before, and ideally longer.
• Avoid a heavy meal, vigorous exercise and alcohol shortly before the test.
• Wear loose clothing that does not restrict deep breathing.
• Tell the team about recent illness, surgery, a heart attack, stroke or eye surgery, as the test may need to be delayed.
• Mention if you have a chest infection, which can affect results and may mean rescheduling.
• Bring your inhalers and a list of medicines.

What happens

A trained operator explains the test and checks it is safe for you to do. You sit down, a soft clip is put on your nose so all your breathing goes through your mouth, and you seal your lips around a mouthpiece.

You take a deep breath in to fill your lungs, then blow out as hard and as fast as you can and keep going until your lungs feel empty. You usually repeat this several times so the best, most consistent results can be used. The operator coaches you, as effort and technique strongly affect the result.

If reversibility is being tested, you use a reliever inhaler and wait around 15–20 minutes, then repeat the blows. The measurements are recorded and usually interpreted afterwards by a specialist, alongside your symptoms and history.

Is this test right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

Spirometry is generally a low-risk test, but the forceful breathing briefly raises pressure inside the chest, so it is usually avoided for a period after events such as a recent heart attack, stroke, collapsed lung, or eye, chest or tummy surgery. Fainting is the most common notable event. Tell the team about your recent medical history and any symptoms so they can decide whether it is safe to proceed.

Published figures to discuss

Spirometry is a safe, non-invasive test for most people, and serious complications are rare. The forceful breathing briefly raises pressure inside the chest, which is why it is avoided for a time after certain surgery or cardiovascular events. Fainting is the most commonly reported notable event. Robust complication percentages are not well established because serious events are so uncommon, so we describe them qualitatively rather than giving invented figures.

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

What happens afterwards

There is usually no physical recovery — most people feel normal within minutes. 'Afterwards' mainly means waiting for the results to be interpreted.

• Brief breathlessness or light-headedness that quickly passes
• A little coughing after the forceful blows
• Feeling tired from the effort for a short while
• Waiting a few days to weeks for the results to be explained

Aftercare

• Resume your normal inhalers and medicines as advised once the test is done.
• Have a drink and rest for a few minutes if you feel light-headed.
• Ask when and how you will get your results.
• Note any symptoms to discuss when the results are explained.
• Attend any follow-up appointment or further tests arranged.
• Contact the clinic if you feel persistently unwell after the test, which is unusual.

• Appointment instructions about pausing inhalers checked
• Inhalers and medicines list brought along
• Note of recent illness, surgery or heart problems
• Loose, comfortable clothing
• Avoided smoking, heavy meals and vigorous exercise beforehand
• Questions about what the result will show
• Clear plan for how results will be shared

⚠ Get urgent help if…

• Chest pain during or after the test — tell the operator immediately or seek urgent help
• Severe or persistent breathlessness that does not settle
• Fainting or feeling you might pass out
• Coughing up blood
• Sudden one-sided chest pain with breathlessness afterwards (very rare)
• Any symptom that feels serious — a breathing test should not leave you unwell

Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your specialist gives you.

Results & realistic expectations

A 'good' result is a set of reliable, consistent measurements that, alongside your symptoms and history, help your specialist understand your lungs. The pattern of FEV1 and FVC, and how they compare with expected values for your age, height, sex and ethnicity, suggests whether your airways are narrowed, your lungs are restricted, or the test is normal.

Spirometry alone does not diagnose a specific condition and a normal test does not rule out all lung disease. It is one piece of the picture, interpreted with your symptoms, examination and sometimes other tests. Poor technique or effort can give misleading results, which is why the test is repeated and quality-checked.

A spirometry result reflects your lungs on the day of the test. Lung function changes over time and with treatment, so the test is often repeated to monitor a condition. How often depends on your diagnosis and how stable you are, which your clinician will advise.

Related tests, treatments or support

Spirometry is often combined with other breathing tests such as gas transfer (transfer factor) and lung volume (body plethysmography) tests when a fuller picture is needed, and with a chest X-ray, CT scan or blood tests depending on your symptoms.

Follow-up & long-term care

Results are usually interpreted by a specialist and discussed at a clinic appointment or by letter. Depending on the findings, you may start or change treatment, have further tests, or be reviewed at intervals. Any abnormal result should have a clear plan for what happens next.

• Repeat the test as advised to monitor a known condition
• Use inhalers and treatments as prescribed between tests
• Keep a symptom or peak flow diary if asked
• Tell the team about new symptoms before a monitoring test

Repeat, follow-on and what comes next

• Blows are repeated several times in one sitting to get reliable, quality-checked results.
• The whole test may need redoing if effort or technique made the results inconsistent.
• Inconclusive results may lead to fuller lung function testing.
• Monitoring tests are repeated over time to track a condition.

Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.

What good aftercare looks like

• Reliable, quality-checked results interpreted by a trained professional.
• A clear explanation of what the result means alongside your symptoms.
• A plan for any further tests, treatment or monitoring.
• Results shared with your GP or referring clinician.
• A contact route if you feel unwell after the test, which is unusual.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

• Whether the test includes reversibility testing, which takes longer
• Where it is done — GP, clinic or hospital lung function lab
• Who interprets the result and reports it
• Whether it is combined with other lung function tests
• Any follow-up consultation to discuss the result
• Whether repeat tests are needed for monitoring

• What the test includes, and whether reversibility testing is part of it
• The fee for the test and for interpretation and reporting
• Whether a consultation to discuss results is included
• Cost of any additional lung function tests if recommended
• What happens, and what it costs, if the test must be repeated
• How and when you receive your results
• Whether results are shared with your GP or referring clinician

On the NHS? Spirometry is widely available on the NHS when clinically indicated; private testing is used mainly for speed or convenience, with the same interpretation.

You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.

Consent traps and marketing red flags

These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.

Choosing a specialist safely

• Check the specialist is on the GMC Specialist Register for this area.
• Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
• You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
• Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
• You're entitled to your total cost in writing — including any follow-up — before you decide.

How Vuemedics verifies every consultant →

Take this to your consultation. A good specialist will welcome every one of these.

• What is this test looking for in my case?
• Do I need to pause any inhalers beforehand, and for how long?
• What will the result change about my diagnosis or treatment?
• What happens if the result is normal, abnormal or inconclusive?
• Will I need reversibility testing or further breathing tests?
• When and how will I get my results, and who explains them?
• Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
• Will you be the specialist who carries out my test, and who looks after me afterwards?
• What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
• What does a realistic result look like — and what can this test not achieve?
• What are my options, including waiting, doing nothing for now, or choosing a different approach?
• Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
• What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Find a verified specialist for spirometry (lung function test)

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How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: Asthma + Lung UK — Spirometry ARTP — Spirometry standards and resources NHS England — Spirometry commissioning guidance Spirometry — StatPearls (NCBI) Royal Free London — Lung function tests: a guide

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.