Asthma – Peak Flow Diary

Asthma – Peak Flow Diary | Health | Patient UK

This leaflet is designed to be printed out for people to record their peak flow reading. A separate leaflet called ‘Asthma – Peak Flow Meter’ describes how a peak flow meter is used, and why peak flow readings are useful, both to diagnose and to monitor asthma.

To take a peak flow reading: put the marker to zero, take a deep breath, seal your lips around the mouthpiece, then blow as hard and as fast as you can into the device. Note the reading. Repeat three times. The ‘best of the three’ is the reading to record on the chart.

What are normal and abnormal peak flow readings?

Normal peak flow readings vary, depending on your age, size, and sex. The range of normal peak flow readings is published on a chart, and doctors and nurses refer to the chart when they check your peak flow reading. In healthy people, peak flow readings vary slightly from time to time. The reading is often slightly higher in the evening compared with the morning.

Below is an example of a two-week diary of peak flow readings done by a child who has quite bad asthma.

References and Disclaimer | Provide feedback


  • Asthma, Clinical Knowledge Summaries (2007)

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