What should you know about breathing tests for asthma?

Spirometry is a common test. You breathe into a mouthpiece, first normally and then with a strong, complete exhalation. The device records how much air you move and how quickly it leaves your lungs. A clinician may repeat the test after an inhaled bronchodilator to see whether airflow improves. Peak-flow readings use a handheld meter and can show changes across the day or during different environments. Results are interpreted alongside symptoms such as wheezing, cough and chest tightness. Allergic rhinitis or house dust mite allergy may coexist with asthma, while chronic cough can have several causes.

A normal result at one visit does not necessarily settle the question if symptoms vary. Your clinician may recommend repeat testing or another assessment when the history and first result do not match.

Follow the clinic’s instructions about inhalers, smoking, meals and strenuous activity; do not stop prescribed medicine unless the clinician tells you to. Wear comfortable clothing and tell the tester if you feel unwell, dizzy or unable to maintain a seal around the mouthpiece. Give a clear account of symptom timing, triggers, night waking and activity limits. Bring your inhalers and any home peak-flow record. The test requires effort, so ask for a pause if coughing or breathlessness interrupts the manoeuvre. A nebuliser treatment is a treatment, not a replacement for diagnostic breathing tests.

Do not wait for a routine test if breathing is severely difficult, you cannot speak normally, your lips look blue or grey, you feel faint, or a prescribed reliever is not helping as directed. Seek prompt assessment for rapidly worsening wheeze, chest tightness or cough. Testing should be arranged when symptoms recur, disturb sleep, limit exercise or follow a consistent trigger, even if you feel well on the appointment day.

Ask: Which inhalers should I use or pause before testing? Will I need spirometry, peak-flow monitoring or repeat testing? What did my result show about airflow? Could allergies or another cause explain my symptoms? What is my action plan if breathing worsens?