Lung Function Tests (Breathing Tests)

What is a lung function test?

A “lung function test” is a simple procedure performed to give the doctor accurate information about your breathing.

Why do I need to have this test?

Your doctor has asked that you have this test so that more detailed information about your breathing will be available. This will enable the doctor to provide you with the most appropriate treatment should it be necessary.

What happens during the test?

Before the test starts the Physiologist will explain the test to you in detail and will answer any questions that you may have regarding it.

The lung function test is a painless procedure. It involves a series of breathing tests consisting of breathing and blowing through different tubes connected to special equipment.

The test will take approximately half an hour to one hour to perform depending on the information requested by the doctor.

Important information

Please inform the clinic co-ordinator (telephone number at the top of your enclosed appointment letter) if any of the following apply to you;

  • If you have coughed up any blood in the last two months.
  • If you have been told by your doctor that you have a collapsed lung.
  • If you have used any medication in the last two months, for chest pain.
  • If you have been told by a doctor you have a blood clot or you have had a heart attack in the last two months.
  • If you currently have or recently have had a chest infection requiring antibiotic treatment.
  • Any surgery in the last two months (including eye surgery).
  • If you feel unwell on the day of the test.

Important instructions

  • If you are currently taking any inhalers, please stop taking them four hours before the appointment time.
  • Please do not smoke for four hours before the test.
  • Please do not drink alcohol for four hours before the test.
  • Please do not partake in any vigorous exercise 30 minutes before the test.
  • Please eat and drink as normal.
  • Please do not wear lipstick or nail varnish to the appointment.

Thank you for your co-operation. This will assist us in obtaining accurate information and enable us to provide you with the most appropriate treatment.

Frequently asked questions

Will I experience any discomfort or side effects?

Some of the breathing tests are tiring, but you will be given time to recover between tests and there are no known side effects associated with this test.

When will I be told the results of my test?

You are usually told your results at your next clinic appointment, or a letter may be sent to your GP or the doctor who referred you for the test.

What should I wear when I attend for my test?

You should wear normal comfortable clothing.

What will happen if I do not want to have this test?

If you do not attend for this test we will not be able to pass important diagnostic information to the doctors. This may affect the medical treatment that you receive. You can choose to have the test or not.


Cooper, B, Evans, A, Kendrick, A and Newall, C (2005)

Practical Handbook of Respiratory Function Testing: Part 1.

Association for Respiratory Technology and Physiology.

How to contact us:

Respiratory Physiology
Gate 12
Level 1
Brunel building
Southmead Hospital
BS10 5NB

0117 414 5400 Monday to Friday, 8am to 6pm

If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.

© North Bristol NHS Trust. This edition published April 2021. Review due April 2023. NBT002296

Lung Function Tests (Breathing Tests)