Asthma Management Handbook
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Table. Severity classification for flare-ups (exacerbations)

Severity Definition Example/s
Mild Worsening of asthma control that is only just outside the normal range of variation for the individual (documented when patient is well)

More symptoms than usual, needing reliever more than usual (e.g. >3 times within a week for a person who normally needs their reliever less often), waking up with asthma, asthma is interfering with usual activities

A gradual reduction in PEF† over several days


Events that are (all of):

  • troublesome or distressing to the patient
  • require a change in treatment
  • not life-threatening
  • do not require hospitalisation.
More symptoms than usual, increasing difficulty breathing, waking often at night with asthma symptoms
Severe Events that require urgent action by the patient (or carers) and health professionals to prevent a serious outcome such as hospitalisation or death from asthma Needing reliever again within 3 hours, difficulty with normal activity

† Applies to patients who monitor their asthma using a peak expiratory flow meter (single PEF measurements in clinic not recommended for assessing severity of flare-ups).

Note: the ATS/ERS Task Force recommended that severe exacerbations should be defined in clinical trials as the use of oral corticosteroids for 3 or more days. However, this definition is not applicable to clinical practice.

Source: Reddel H, Taylor D, Bateman E et al. An official American Thoracic Society/European Respiratory Society statement: asthma control and exacerbations: standardizing endpoints for clinical asthma trials and clinical practice. Am J Respir Crit Care Med 2009; 180: 59-99. Available at:

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