Hypersensitivity Pneumonitis Clinical Presentation

Updated: Oct 08, 2020
  • Author: Caleb Hsieh, MD, MS; Chief Editor: John J Oppenheimer, MD  more...
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The clinical presentation of hypersensitivity pneumonitis (HP) is categorized as acute, subacute, or chronic, according to duration of illness.

Acute hypersensitivity pneumonitis clinical presentation is as follows:

  • Flulike syndrome including fever, chills, malaise, cough, chest tightness, dyspnea, and headache

  • Develops within hours following significant exposure

  • Symptoms typically resolve gradually within 12 hours to several days following exposure removal

  • May recur following re-exposure

Subacute (intermittent) hypersensitivity pneumonitis clinical presentation is as follows:

  • Insidious onset of productive cough, dyspnea, fatigue over weeks to months

  • Progression to persistent cough and dyspnea

  • May occur in individuals with frequent acute reactions

  • May note anorexia and/or weight loss

Chronic hypersensitivity pneumonitis clinical presentation is as follows:

  • May have unrecognized or untreated acute/subacute disease

  • Often presents with no obvious acute episodes, presents as insidious disease

  • Progressive dyspnea, cough, fatigue, malaise, and/or weight loss


Physical Examination

Physical examination findings of hypersensitivity pneumonitis (HP) vary according to clinical presentation.

Patients with acute hypersensitivity pneumonitis present with fever, tachypnea, and diffuse fine bibasilar crackles upon auscultation.

Patients with subacute hypersensitivity pneumonitis present similarly to patients with acute disease, but symptoms are generally less severe and have lasted longer.

Patients with chronic hypersensitivity pneumonitis present with muscle wasting and weight loss. Clubbing is observed in 50% of patients. Tachypnea, respiratory distress, and inspiratory crackles over lower lung fields often are present.

Acute on chronic hypersensitivity pneumonitis is generally severe and often presents with respiratory distress requiring ventilation assistance.