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Asthma Health Center

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Asthma Diary - Topic Overview

An asthma diary helps you keep track of how well you are managing your asthma.

If you have symptoms or an asthma attack, record the trigger (if possible), the symptoms, and what kind of medicine you used for relief and how well it worked. Also note if you had to contact your doctor or seek emergency care. This can help you know your triggers and help your doctor monitor your treatment.

If your doctor recommends it, measure your peak expiratory flow (PEF) often, every morning and evening if possible, and record it in your diary. It may be helpful to record your PEF using the same green, yellow, and red zone system used in your asthma action plan.

Here is an example of how to use an asthma diary if you are keeping track of peak flow.

Week of October 12

My personal best peak flow is 400 liters per second. My:

  • Green zone is 320 to 400 liters per second (80% to 100% of my personal best). To figure 80% of your personal best peak flow, multiply your best flow (in this example, 400) by 0.80 (in this example, you get 320).
  • Yellow zone is 200 to 319 liters per second (50% to less than 80% of my personal best). To figure 50% of your personal best peak flow, multiply your best flow (in this example, 400) by 0.50 (in this example, you get 200).
  • Red zone is less than 200 liters per second (less than 50% of my best).

My current long-term (controller) medicine is fluticasone.

Example of an asthma diary
Date AM/PM PEF Trigger Symptoms Quick-relief medicine and response Red zone visit to doctor/hospital?





350 a.m.

300 p.m.


Improved PEF





Eliminated wheezing


Click here for a blank asthma diary template(What is a PDF document?).

    WebMD Medical Reference from Healthwise

    Last Updated: /2, 14 1
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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