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Last reviewed: 16 Mar 2025
Last updated: 15 Apr 2025

Summary

Definition

History and exam

Key diagnostic factors

  • cough
  • wheezing
  • shortness of breath
  • chest tightness
  • sleep disturbance
  • accessory muscle use
  • tachypnea
  • tachycardia
  • wheezing, poor air movement, or diminished breath sounds
  • inability to speak

Other diagnostic factors

  • exercise limitation
  • altered consciousness
  • stridor
  • cyanosis

Risk factors

  • viral infection
  • uncontrolled asthma symptoms
  • high use of short-acting beta-2 agonists
  • inconsistent use of inhaled corticosteroids
  • incorrect inhaler technique
  • low forced expiratory volume in 1 second (FEV₁)
  • high bronchodilator responsiveness
  • current smoker (including e-cigarettes/vapes) or exposure to secondhand cigarette smoke
  • exposure to allergens (including history of seasonal allergic rhinitis)
  • air pollution
  • poor indoor air quality
  • obesity
  • chronic rhinosinusitis
  • gastroesophageal reflux disease
  • confirmed food allergy
  • history of asthma
  • history of hospitalization for asthma exacerbations
  • one or more severe exacerbations in the last 12 months
  • use of oral corticosteroids
  • poor adherence to asthma treatment
  • pregnancy
  • psychological or socioeconomic problems
  • elevated blood eosinophils
  • elevated fractional exhaled nitric oxide (FeNO)
  • respiratory bacterial infection

Diagnostic tests

1st tests to order

  • oxygen saturation
  • peak expiratory flow rate

Tests to consider

  • ABG
  • chest x-ray
  • CBC
  • metabolic panel for electrolytes, BUN levels, creatinine

Treatment algorithm

Contributors

Expert advisers

Sourav Majumdar, MD

Clinical Assistant Professor (Affiliated)

Division of Pulmonary, Allergy and Critical Care Medicine

Department of Medicine

Stanford University School of Medicine

Stanford

CA

Disclosures

SM declares that he has no competing interests.

Lauren Eggert, MD

Clinical Assistant Professor

Division of Pulmonary, Allergy and Critical Care Medicine

Department of Medicine

Stanford University School of Medicine

Stanford

CA

Disclosures

LE declares that she has participated on advisory boards for Regeneron and AstraZeneca.

Acknowledgements

Dr Sourav Majumdar and Dr Lauren Eggert would like to gratefully acknowledge Dr Ware Kuschner, Dr Michael Ezzie, and Dr Jonathan P. Parsons, the previous contributors to this topic.

Disclosures

WK and ME declare that they have no competing interests. JPP is a member of Speakers' Bureaus for GlaxoSmithKline, Schering-Plough, and AstraZeneca.

Peer reviewers

Anne Dixon, MD

Assistant Professor

Pulmonary and Critical Care Medicine

University of Vermont

Burlington

VT

Disclosures

AD declares that she has no competing interests.

Neil C. Thomson, MBChB, MD, FRCP

Professor of Respiratory Medicine

Institute of Infection, Immunity & Inflammation

University of Glasgow

Glasgow

Scotland

UK

Disclosures

NCT declares that he has no competing interests.

Graeme P. Currie, MBChB, MD, FRCP

Consultant Chest Physician

Chest Clinic C

Aberdeen Royal Infirmary

Aberdeen

Scotland

UK

Disclosures

GPC declares that he has no competing interests.

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