Occupational asthma

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 10 Aug 2025

Last updated: 12 Jan 2024

Occupational asthma should be suspected in all adult patients with asthma.

An occupational history should be taken to identify work-related causes. Details of work exposures should be obtained from material safety data sheets and other material available to the patient from their workplace.

Objective evidence of asthma should be obtained from spirometry, a bronchodilator response, and/or a methacholine challenge. Tests should be performed when the patient is symptomatic and/or within days of having exposure to a suspected aetiological agent.

If sensitiser-induced occupational asthma is suspected, additional testing of asthma should be done, preferably while the patient is still working. Whenever possible an immunological response to a suspected work sensitiser should be demonstrated by skin or in vitro tests.

In sensitiser-induced occupational asthma, removal from any further exposure to that agent should be recommended.

In irritant-induced occupational asthma, preventive measures should be implemented in the workplace to reduce future exposures and episodes.

For all causes of occupational asthma, the clinician should continue treating the asthma as appropriate, assist in the initiation of any appropriate compensation claim, and consider other workers at risk.

Definition

Occupational asthma (OA) is asthma caused by the workplace and may result from immunological or non-immunological stimuli.[1] There are 2 main forms. Sensitiser-induced OA is caused by immunological stimuli and develops after a latency period between first exposure and the onset of symptoms.[2][3] Irritant-induced OA (including reactive airways dysfunction syndrome) is caused by non-immunological stimuli.[4]

History and exam

Key diagnostic factors

presence of risk factors
occupational exposure to sensitising agents or irritants
symptoms of asthma that improve during holidays
initial onset of asthma symptoms during a work period

Full details

Risk factors

high-level exposure to sensitiser
atopy
genetic factors
smoking

Full details

Diagnostic investigations

1st investigations to order

spirometry
chest x-ray
skin prick testing
specific serum IgE assay
non-specific bronchial hyper-responsiveness (NSBHR)
serial peak expiratory flow rate (PEFR)

Full details

Investigations to consider

specific inhalation challenge (SIC)

Full details

Emerging tests

induced sputum cytology
fractional exhaled nitric oxide (FeNO)

Treatment algorithm

ACUTE

sensitiser-induced

irritant-induced

ONGOING

symptomatic asthma

Contributors

Authors

Ryan Hoy, MB BS, MOEH, FRACP

Respiratory Physician

The Alfred Hospital

Melbourne

Victoria

Australia

Disclosures

RH declares that he has no competing interests.

Susan M. Tarlo, MB BS FRCP(C)

Professor of Medicine

University of Toronto

Respiratory Physician

Toronto Western Hospital

Toronto

Ontario

Canada

Disclosures

SMT has received research grants from Ontario Workplace Safety and Insurance Board (WSIB) for a systematic review of work-related COPD and from the Centre for Research Expertise in Occupational Diseases, funded by Ontario Ministry of Labour. As part of her clinical practice she assesses patients referred by the WSIB and the Workplace Safety and Insurance Appeals Tribunal.

Peer reviewers

Ware Kuschner, MD

Associate Professor of Medicine

Stanford University

Stanford

Staff Physician

US Department of Veterans Affairs

Palo Alto Health Care System

Palo Alto

Disclosures

WK declares that he has no competing interests.

Karin Pacheco, MD

Associate Professor of Medicine

National Jewish Medical Centre

Denver

Disclosures

KP declares that she has no competing interests.

Philip Harber, MD

Professor of Medicine

University of California

Los Angeles

Disclosures

PH declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Tarlo SM, Balmes J, Balkissoon R, et al. Diagnosis and management of work-related asthma: American College of Chest Physicians Consensus Statement. Chest. 2008 Sep;134(3 suppl):1S-41S. Abstract

American College of Radiology. ACR Appropriateness Criteria: occupational lung diseases. 2019 [internet publication].Full text

British Thoracic Society. BTS clinical statement: occupational asthma. Mar 2022 [internet publication].Full text

Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. Jul 2023 [internet publication].Full text

Baur X, Sigsgaard T, Aasen TB, et al. Guidelines for the management of work-related asthma. Eur Respir J. 2012 Mar;39(3):529-45.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Work-exacerbated asthma
- Occupational eosinophilic bronchitis
- Coincidental non-occupational asthma
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Guidelines
- Global strategy for asthma management and prevention
- Global strategy for asthma management and prevention
More Guidelines
Patient information
Asthma in adults: what is it?
Asthma in adults: what treatments work?
More Patient information
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Occupational asthma

Summary

Definition

History and exam

Key diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Emerging tests

Treatment algorithm

sensitiser-induced

irritant-induced

symptomatic asthma

Contributors

Authors

Ryan Hoy, MB BS, MOEH, FRACP

Disclosures

Susan M. Tarlo, MB BS FRCP(C)

Disclosures

Peer reviewers

Ware Kuschner, MD

Disclosures

Karin Pacheco, MD

Disclosures

Philip Harber, MD

Disclosures

Peer reviewer acknowledgements

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice