Hypersensitivity pneumonitis is inflammation of the lungs due to breathing in a foreign substance, usually certain types of dust, fungus, or molds.
Extrinsic allergic alveolitis; Farmer's lung; Mushroom picker's disease; Humidifier or air-conditioner lung; Bird breeder's or bird fancier's lung
Causes, incidence, and risk factors
Hypersensitivity pneumonitis usually occurs in people who work in places where there are high levels of organic dusts, fungus, or molds.
- Bird fancier's lung is the most common type of hypersensitivity pneumonitis. It is caused by repeated or intense exposure to proteins found in the feathers or droppings of many species of birds.
- Farmer's lung is caused by exposure to dust from moldy hay, straw, and grain.
These exposures can lead to lung inflammation and acute
Hypersensitivity pneumonitis may also be caused by fungi or bacteria in humidifiers, heating systems, and air conditioners found in homes and offices. Exposure to certain chemicals, such as isocyanates or acid anhydrides, can also lead to hypersensitivity pneumonitis.
Review Date: 06/10/2011
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.