Hypersensitivity pneumonitis (HP)

The hypersensitivity pneumonitis (HP) fact sheet has been designed to provide an understanding of the causes, symptoms and diagnosis of HP. The resource provides information to help people living with HP on symptom management and an overview of the treatments available for HP.

Hypersensitivity Pneumonitis (HP) is a rare lung condition caused by an immune reaction to inhaled allergens such as dust, mould, bird droppings, or bacteria. These substances trigger inflammation in the lungs (pneumonitis), which can lead to chronic lung damage if exposure continues. HP is more likely to affect individuals who work or live in environments with frequent exposure to organic materials—such as farmers, bird breeders, gardeners, or musicians using wind instruments.

Common symptoms of HP include dry cough, breathlessness, wheezing, fatigue, fever, and weight loss. Symptoms may improve when the person is away from the source of exposure, such as during holidays. However, prolonged or repeated exposure can lead to fibrotic HP, a form of permanent lung scarring.

Diagnosis involves a detailed medical history, physical examination, and tests such as chest X-rays, CT scans, lung function tests, and blood tests. In complex cases, procedures like bronchoscopy or lung biopsy may be required. Despite thorough investigation, the specific allergen causing HP is not identified in up to two-thirds of cases.

Treatment focuses on avoiding the allergen to prevent further lung inflammation. Medications like anti-inflammatory drugs (e.g., prednisone) and anti-fibrotic drugs (e.g., nintedanib) may be used. Quitting smoking, vaccinations, pulmonary rehabilitation, and oxygen therapy are also recommended.
Prognosis varies; avoiding allergens can reverse lung inflammation in some cases, but fibrotic HP, which involves permanent lung scarring, may worsen even with treatment. It is important to discuss your individual circumstances with your healthcare professional.

If you or someone you know is affected by HP, reaching out to the Lung Foundation Australia can provide valuable support and information. They are dedicated to helping patients navigate their journey and access the best possible care. For more information and support, individuals can contact the Lung Foundation Australia’s Information and Support Centre at 1800 654 301.