Symptoms vary widely from one individual to another with the same histopathologic (lung biopsy) diagnosis. Individual patients, however, tend to consistently present the same pattern unless there are changes in the levels of exposure to the offending antigen(s). Partial remediation has been noted to convert acute or subacute to insidious-type presentations placing the patient at greater risk of long-term damage to the lung.

Acute: This type of presentation is the easiest to work with since symptoms require
immediate medical attention. Abrupt onset of cough, fever, chest pain, shortness
of breath, and tiredness and fatigue are the most common symptoms. Other
symptoms that may be seen include body aches, chest rattles and wheezes,
nasal congestion, and mild mental confusion.

Subacute: This type of presentation is less intense than the acute presentation. Symptoms often start as throat clearing and a hacky cough, intermittent low grade fever,
breathlessness, and tiredness and fatigue. These patients are more difficult
to diagnose early in the course because of similarity to other more common
respiratory tract disorders. Symptoms that may occur later in the course include
weight loss, body aches, extreme fatigue, shortness of breath and chest rattles and
wheezes.

Insidious: This type of presentation may be very gradual without any significant symptoms until shortness of breath associated with activity and a slight non-productive
cough is noted. Loss of appetite, weight loss, and tiredness and fatigue are also
commonly observed signs and symptoms. This is the most dangerous presen-
tation since fibrosis may become advanced before the patient is diagnosed.

There are no clear delineations between these presentations, rather a spectrum ranging from the very acutely intense to very low-level asymptomatic patients. The type of presentation probably depends upon a number of factors including the level of antigen exposure, the sensitivity of the individual, potency of the antigen, and others.