Clinical Manifestations of Pneumonia

Worldwide, pneumonia kills more people than any other infectious disease 1. In the U.S. alone, each year pneumonia accounts for more than 1 million hospitalizations. A variety of microorganisms, including bacteria, viruses and fungi, can infect your lungs and cause pneumonia, and these different organisms can lead to somewhat different signs and symptoms. The clinical manifestations of pneumonia -- the clues a doctor uses to diagnose the disease -- may be influenced by your age or underlying medical conditions 2.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Typical Signs and Symptoms

Like other types of infection, pneumonia can trigger fever, chills, rapid heart rate, body aches and weakness. Because pneumonia affects your lungs, it typically causes rapid breathing and a cough, which may or may not produce phlegm. The phlegm may be clear, yellow, greenish or blood-tinged. Pleuritic pain -- sudden, sharp chest pain when you inhale -- is common in people with pneumonia. When listening to your lungs, your doctor may hear crackles, pops, wheezes or other unusual sounds from the infected lung, and the breath sounds on one side may be quieter than the other.

X-Ray and Laboratory Evaluation

Although your doctor may suspect you have pneumonia based on your symptoms and a physical examination, a chest x-ray is usually needed to confirm the diagnosis. Depending on the organism involved, your x-ray may show a focal infiltrate, which shows up as an abnormal bright area in one region of your lung, or it could simply reveal nondescript haziness throughout your lungs. There might be fluid at the base of one or both lungs, which is often a sign of bacterial pneumonia.

Laboratory tests are not needed to diagnose pneumonia, but they may help gauge the severity of your infection or identify a specific organism. An elevated white blood cell count is common with pneumonia, but people with pneumonia often have normal white counts. A low blood glucose level or decreased blood oxygen level may signify severe infection and an increased risk for complications. Blood and sputum cultures, nasal swabs or urine or blood antigen tests may pinpoint a particular infectious agent, which can guide therapy.

Atypical Symptoms

Some people with pneumonia, particularly the elderly, may not have typical symptoms. Older people may not develop the fever, chills or cough that typically accompany pneumonia, according to a March 2012 review in “The Journals of Gerontology.” Rather, they may have symptoms mistakenly attributed to aging, such as confusion, disorientation, loss of appetite or falling.

While infants and young children with pneumonia typically have a cough and fever, they may also have grunting, nasal flaring, increased respiratory rate and retractions, which are inward movements of the spaces between the ribs and above the collarbone when they inhale. Rapid breathing is a useful diagnostic sign in children with pneumonia, but any illness that causes fever can trigger rapid breathing in children.

Certain types of pneumonia, such as Legionnaires' disease, may manifest with atypical symptoms, such as severe headache, confusion or diarrhea. If your doctor is not aware you have been exposed to an unusual infectious agent, your diagnosis could be delayed. If you have an underlying medical condition, such as heart failure, sudden shortness of breath could wrongly be attributed to worsening of your heart condition, rather than pneumonia.


Although pneumonia is easily recognizable in most people, there is no specific set of clinical manifestations that can diagnose or rule out pneumonia in all cases. When evaluating a person for pneumonia, the doctor must be aware of the types of illnesses circulating in the community and pursue any possible exposures to unusual agents while keeping the unique characteristics of each patient in mind. If you think you or a family member have pneumonia, see your doctor promptly for an evaluation.