Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

all patients

1st line – avoidance of antigen

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ACUTE
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all patients
1st line – 

avoidance of antigen

Recommended in all patients.

Although there is limited information regarding effectiveness, clinically it is a sensible option.[6][43][67][68]

The time it takes for symptoms to reduce is antigen-dependent, environment-dependent, and patient-dependent.

Plus – smoking cessation ± pulmonary rehabilitation ± supplemental oxygen

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ACUTE
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all patients
Plus – 

smoking cessation ± pulmonary rehabilitation ± supplemental oxygen

Treatment recommended for ALL patients in selected patient group

Patients who continue to smoke cigarettes should be counselled to quit.

Many patients will benefit from pulmonary rehabilitation programmes to improve their functional status and quality of life.[63]​​[64]​​

Severe hypoxaemia (PaO₂ ≤55 mmHg or oxygen saturation ≤89%) at rest or with exertion should be managed with supplemental oxygen. This is strongly recommended by the 2020 American Thoracic Society guideline on home oxygen therapy for adults with chronic lung disease.[65][Evidence C]

Consider – corticosteroid

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ACUTE
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all patients
Consider – 

corticosteroid

Additional treatment recommended for SOME patients in selected patient group

Indications for corticosteroid treatment include persistent acute symptoms despite avoidance of antigen; moderate to severe respiratory impairment (e.g., hypoxaemia, lung function tests); and/or extensive lung involvement on imaging.

Patients with chronic fibrotic hypersensitivity pneumonitis (HP) are often given corticosteroids, for example, if there is evidence of inflammation such as bronchoalveolar lavage lymphocytosis or ground glass opacities.[43][47][57][58]

In patients with an acute presentation corticosteroids are given for 1-2 weeks, and can then usually be tapered off over about 6 weeks (alongside antigen avoidance). Patients with chronic fibrotic HP may require longer-term maintenance treatment. Follow your local protocols.

Primary options

prednisolone: 0.5 to 1 mg/kg/day orally initially, taper dose according to response

Consider – immunosuppressant

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ACUTE
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all patients
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chronic fibrotic disease
Consider – 

immunosuppressant

Additional treatment recommended for SOME patients in selected patient group

In patients with chronic fibrotic disease, an immunosuppressant such as azathioprine or mycophenolate may be started in patients with a suboptimal response to corticosteroids, or in patients who have a moderate to high corticosteroid dose requirement.[47]​ After starting the immunosuppressant, the corticosteroid dose is generally tapered, and then maintained at a low dose.

Observational studies suggest that immunosuppressants can improve lung function and reduce corticosteroid dose with patients with chronic or fibrotic hypersensitivity pneumonitis, but randomised clinical trials are needed.[59][60][61][62]

Primary options

azathioprine: 1.5 to 2 mg/kg orally once daily, maximum 200 mg/day

OR

mycophenolate mofetil: 500-1500 mg orally twice daily

Consider – lung transplant

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ACUTE
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all patients
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progressive fibrotic disease
Consider – 

lung transplant

Additional treatment recommended for SOME patients in selected patient group

As for patients with other interstitial lung diseases, lung transplantation may be considered in eligible patients with progressive fibrotic disease.[1][66]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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