According to duration of illness, the clinical presentation of Hypersentivity Pneumonitis is categorized as Acute, Subacute, or Chronic.

• Symptoms develop 4-6 hours following exposure to the inciting agent and then generally resolve spontaneously within 12 hours to several days upon removal of the inciting agent.
• Symptoms include the abrupt development of
  • fever
  • chills
  • malaise
  • cough
  • chest tightness
  • dyspnea
  • headache
  • malaise.

• Symptoms include the gradual development of
  • productive cough
  • dyspnea
  • fatigue
  • anorexia
  • weight loss

• The same symptoms may be present in patients who experience acute attacks on multiple occasions.

Patients with subacute HP present similarly to patients with acute disease, but symptoms are less severe and last longer.

Patients often lack a history of acute episodes.

They have an insidious onset of cough, progressive dyspnea, fatigue, and weight loss.

Removing exposure results in only partial improvement.