How long does spirometry take to work for COPD?

During spirometry, you breathe into a mouthpiece several times so the clinician can assess how much air you move and how quickly you blow it out. The test may be repeated after an inhaled medicine to compare airflow. It gives an assessment at the time of testing, rather than gradually changing COPD itself.

A clinician may discuss an initial impression on the day, but results can need checking alongside your symptoms, examination and medical history. Spirometry can support a COPD assessment, but it is only one part of understanding your breathing.

Follow the clinic’s instructions about eating, smoking, exercise and whether to pause any inhaler. Bring a list of medicines and describe your usual cough, phlegm, wheeze and breathlessness. After testing, ask when the report will be reviewed and how it will affect your inhaler plan.

Do not change prescribed treatment because of a single reading. Keep using your medicines as directed unless the clinician gives different instructions. More detail is available in [Spirometry](/treatments/diagnostics-and-screening/spirometry/) and [COPD](/conditions/copd/).

Seek urgent medical help if breathing becomes suddenly or severely difficult, you cannot speak comfortably because of breathlessness, your lips look blue or grey, or you feel faint or confused. Contact your clinician promptly if breathlessness, cough or phlegm is worsening and your usual reliever is not helping.

Ask what your result shows, whether the test was reliable, when it will be reviewed, and whether another breathing assessment is needed. You can also ask which symptoms should trigger an earlier appointment.