Classifying Asthma Severity

Reviewed by: HU Medical Review Board | Last reviewed: January 2023

Asthma varies in how often you have symptoms and how intense those symptoms are. This is referred to as your “asthma severity.” Your doctor will assess your asthma severity as part of diagnosing you with asthma. Knowing your asthma severity can help your doctor decide on the right treatments for you.1

Your asthma action plan will account for your asthma severity. If symptoms get worse or more frequent, talk to your doctor. Your doctor can help you figure out whether you need different treatments to control your asthma.

Why is it important to know the severity of your asthma?

Doctors decide which treatment to try first based on the severity of your asthma. More severe asthma may require more intense treatments. Doctors evaluate the severity of your asthma when you are not yet taking daily medicine to control it.1

The severity of asthma can change over time. So your doctor may need to reassess the severity of your asthma once in a while. Things that affect severity include:1

How do doctors assess asthma severity?

Experts have different guidance for assessing asthma severity. In general, doctors use several criteria, such as:1

  • Frequency and intensity of daytime symptoms in the past month
  • Disruptions in sleep and other activities because of symptoms
  • Lung function (using a spirometry test)
  • Frequency of rescue inhaler use
  • Frequency of oral corticosteroid use

If you take daily medicine to control your asthma, your doctor will assess how well your asthma is controlled. This will take into account your daily medicine use. Doctors may assess asthma control at every visit. This can help them decide on changes to treatments.1

What are the types of asthma severity?

There are 4 main types, or levels, of asthma severity. The severity of your asthma is based on its most severe feature. Features are listed below, by severity.

Intermittent

Intermittent asthma means that you have occasional symptoms. It is also called “well-controlled” asthma. Features of intermittent asthma include:2

  • Symptoms happening 2 or fewer days per week
  • Symptoms waking you up 2 or fewer times per month
  • Using your rescue inhaler 2 or fewer days per week
  • No interference with school, work, or other activities
  • Lung function tests having normal or near-normal results

Treatment involves using a quick-relief inhaler as needed. You usually do not need daily control drugs.3

Mild persistent

Mild persistent asthma means that you have regular symptoms. Features of mild persistent asthma include:2

  • Symptoms happening more than 2 days a week (but less than daily)
  • Symptoms waking you up 3 to 4 times per month (but less than weekly)
  • Using your rescue inhaler more than 2 days per week (but less than daily)
  • Minor interference with school, work, or other activities
  • Lung function tests having near-normal results

Treatment involves daily low-dose inhaled corticosteroids (ICSs). Your doctor may also suggest other treatment options.3

Moderate persistent

Moderate persistent asthma means that you have symptoms every day. Other features of moderate persistent asthma include:2

  • Symptoms waking you up weekly
  • Using your rescue inhaler every day
  • Limiting your normal activities
  • Spirometry showing decreased lung function

Treatment involves daily low-dose ICSs with long-acting beta-agonists (LABAs). Your doctor may also suggest other treatment options.3

Severe persistent

Severe persistent asthma means that you have symptoms every day, throughout the day. Other features of severe persistent asthma include:2

  • Symptoms waking you up every night
  • Using your rescue inhaler several times a day
  • Extreme activity limitation
  • Spirometry showing medium-low or very low lung function

Treatment involves medium-dose or high-dose ICS-LABAs. Your doctor may also suggest other treatment options. Asthma specialists may help in treatment.3

Some people with severe asthma have uncontrolled asthma even with treatment. This is called “difficult-to-treat” or “treatment-resistant” asthma. Your doctor will work with you to try to modify things that make your asthma treatment-resistant. These might include triggers, inhaler techniques, and other chronic conditions. Your doctor might also suggest trying other medicines, such as biologics.1,3

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