Keeping an Asthma Diary

Reviewed by: HU Medical Review Board | Last Reviewed: May 2016. | Last updated: March 2021

You are the expert on your own asthma. You know better than anyone else how often symptoms bother you and what situations trigger them. Keeping track of your asthma can help your health care provider to understand how your asthma is affecting you. One way to do this is to keep a daily asthma diary.

Why keep a diary?

There are many reasons to keep an asthma diary.1 Having a diary can help you to get the most out of your office visit. You can report the details about your asthma accurately and quickly to your provider. This frees up time to discuss the best treatment plan.

Monitoring a new treatment

After you start or change medications, it is a good idea to see how the new treatment affects your asthma. It can take two weeks before inhaled corticosteroids make a noticeable difference. The frequency of symptoms and nighttime waking are important measures of asthma control. Keeping a diary will help you and your provider know how well controlled your asthma is.

Getting your best peak flow measurement

You can monitor your lung function at home using a peak flow meter. The peak flow meter is a handheld, portable device that measures how well air moves out of your lungs.1 To figure out your best peak flow measurement, you measure twice a day for two to three weeks and record the results in your diary. Your highest measurement is your personal best. Your best peak flow measurements can be used to create a written Asthma Action Plan to manage your asthma.

Identifying triggers

One way to manage your asthma is to avoid the things that make your asthma worse. There are dozens of potential asthma triggers, making it difficult to sort out which affect you. A diary may help you to find a pattern to your asthma symptoms, which can narrow the list of triggers. You might find a diary helpful if you suspect that your asthma is work-related.


A diary can be helpful when first diagnosing asthma. Your health care provider will want details about symptoms such as coughing, wheezing, or shortness of breath. Your provider will want to know how often you have had those symptoms in the previous two to four weeks.1,2 He or she will ask when you have symptoms most often, for example, at night, in the morning, after being active, or at certain times of year.

What should my diary include?

The information that you record will depend on the reason why you are keeping a diary. It should be detailed enough to be helpful. However, if it is too much work, it will be hard to keep up with it.

Things to consider including in your diary are:

  1. Date
  2. Symptoms: type and time of day
  3. Peak flow readings (if you are using your peak flow meter)
  4. Nighttime waking due to asthma
  5. Medication use, especially your rescue inhaler
  6. Limitations on your activities because of asthma

You should keep a copy of your written Asthma Action Plan with your diary. Compare your peak flow readings or symptoms with the zones on your plan and take steps as needed.

Consider keeping a current list of all medications in your diary. Some asthma medications interact with other medications or supplements, so it is a good idea to review your medications with your health care provider at each visit.

Symptoms versus peak flow measurements: Which is better for monitoring asthma?

Keeping track of your symptoms or peak flow measurements work equally well for monitoring asthma for most adults.1 For people with more severe asthma, peak flow monitoring may be better. Symptom monitoring may be better than peak flow for children. Symptoms are easier for families to record consistently. You and your health care provider should decide what will work best for you and your family.

What kinds of asthma diaries are there?

Asthma diaries come in many forms. The key is consistency, so you can use whatever works best for you. A simple paper diary can do the trick. Your health care provider may be able to provide you with a blank log to fill out. You also can find many different forms on the internet. Keep the form with your peak flow meter or medications. Alternatively, you can keep in some place you see often, such as the refrigerator or bathroom mirror.

A number of smartphone apps are also available to help with asthma management. Along with a symptom diary, these apps may include medication reminders and peak flow charts. Some allow you to send information to your health care provider.

Do asthma diaries work?

Keeping a diary might improve asthma management. Use of web-based diaries was studied in 228 children and teens from the Netherlands.3 Nearly everyone (89%) completed the diary over the four week study. They compared the diary information with standard questionnaires that measure asthma control and quality of life. The results showed that the online diary was as good as the questionnaires for evaluating symptoms and asthma control.

A diary may help you to notice when your asthma is getting worse and an attack is likely. Nearly 170 participants in one study kept an electronic diary for one year.4 Researchers compared the data in the diaries with the date and frequency of asthma attacks. They found that two simple patterns identified 65% of asthma attacks:

  • 20% decrease in peak flow or
  • 20% increase in symptoms for two days in a row.

However, not all studies show that diaries improve asthma management.5 One study of 340 children included 86 children who kept a diary. Keeping a diary did not reduce emergency department visits, hospitalizations, or medication use, or improve lung function.

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