Breathing and lung function tests

Getting ready for your breathing test

Breathing keeps us alive. It provides the oxygen that our bodies need and removes carbon dioxide, the waste gas that our cells produce as they use energy. If you have problems with your breathing, your health care professional may suggest taking one or more tests.

On this page:


What are breathing and lung function tests for?

Breathing and lung function tests can help health care professionals to work out:

  • if your lungs are working normally, or if there is a problem
  • if there is a problem, what type of problem it is
  • if there is a problem, how severe it is.

What can I expect from my breathing tests?

Different people may need more or less complicated tests. Sometimes the tests need to be done only once to see what the problem is. Sometimes they are repeated to monitor changes over time or how you respond to treatment.

Health care professionals will run your tests. They will make sure the equipment gives an accurate result. They’ll also make sure that it is hygienic to use. For example, there will be a separate, disposable mouthpiece for each person.

When will I get the results, and what do they mean?

You may not get your results on the day. You may have to wait until you see your consultant, as they may need to interpret the results. When you have the test, ask when your results will be ready.

When you get your results, ask your health care professional to explain them to you. Keep asking questions until you understand what your results mean.

It’s a good idea to ask for a hard copy of your results, to keep and take with you to other health care appointments.

The results of tests can be used together with your medical history, symptoms and examination results as well as X-rays and scans. All this information will help guide your treatment.

How can I prepare for my breathing test?

When you’re going for a test, you may get a leaflet or letter with instructions. Read them carefully before your test. For some tests, you may be asked:

  • to wear loose-fitting clothing, or suitable shoes for a walking test
  • not to smoke for 24 hours before the test (if you smoke, this can alter the results of some tests)
  • to avoid eating for some hours before
  • to avoid drinking alcohol and caffeinated drinks (like coffee, tea, cola or energy drinks) for some hours before
  • not to take your medication for some hours before
  • to bring along your medication, such as inhalers

If you’re not sure how to prepare, get in touch with the person who made the appointment for you.

If you’ve had a chest infection or a flare-up of symptoms and taken drugs such as steroids or antibiotics to treat it, this may affect your test results. If your test appointment is within 4–6 weeks of this, check with your health care professional about going ahead. Remember to tell whoever does your test about your recent chest infection and the drugs used to treat it.

Questions to ask about your breathing or lung function test

You may have specific or detailed questions about your breathing or lung function tests. It’s good to write these down and take them with you to your appointment. If you’re not sure what to ask, here are some suggested questions:

  • What is the test for?
  • Who will carry out the test, and where?
  • What will happen during the test and how long does it take?
  • Do I need to prepare for the test?
  • Will there be any side effects and how long will they last?
  • How and when will I get the results?

What types of breathing and lung tests are there?

Different breathing and lung function tests can give different information. You might have tests to measure:

Doctors might also want to know more about what’s happening inside their lungs. You might have imaging scans or investigations to look inside your lungs, to give a better picture of your lung health.

We have information about what each test involves:

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Last medically reviewed: January 2020. Due for review: January 2023

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.