Hypersensitivity Pneumonitis: Symptoms & Signs

Medically Reviewed on 12/12/2019

Hypersensitivity pneumonitis is an inflammation of the lungs. It usually occurs 4-12 hours after breathing the affected air.

Signs and symptoms of hypersensitivity pneumonitis include

The symptoms resemble those of a flu-like illness. The sudden onset of the illness usually occurs after heavy exposure to the irritant, while long-term or chronic hypersensitivity pneumonitis occurs after prolonged lower-level exposure. Scarring (fibrosis) of the lung can occur in chronic cases.

Causes of hypersensitivity pneumonitis

The body's immune reaction to small particles in the air causes hypersensitivity pneumonitis. Different kinds of particles in the air, including bacteria, fungi, mold, or even chemicals or inorganic substances, can cause the inflammatory reaction.

Other hypersensitivity pneumonitis symptoms and signs


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.