What Is Pneumonia?

It’s pretty common to develop a cough or an upper respiratory infection in the winter. Most of the time you get over it quickly. But sometimes a winter illness can develop into pneumonia, a lung infection that is particularly dangerous for older adults.

In a typical year, about 1.4 million Americans go to the emergency room with pneumonia and more than 41,000 people die of the disease, according to the Centers for Disease Control and Prevention (CDC).

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Pneumonia can cause severe illness in people of any age, but children under age 5 and older adults are the most vulnerable. A 2018 study in Singapore found that more than 1 out of every 6 adults age 65-plus who are hospitalized with pneumonia die from the infection.

People who smoke, have weak immune systems or suffer from chronic conditions such as lung disease or heart disease are at higher risk.

Causes and diagnosis

Pneumonia can be caused by bacteria, fungi or viruses, including the ones that cause the flu, respiratory syncytial virus (RSV) and COVID-19. 

The vast majority of people with pneumonia have bacterial infections, but recent data suggests that viruses cause more cases than doctors previously realized. Bacterial pneumonias tend to be more severe than those caused by viruses.

It’s not unusual to develop bacterial pneumonia while your body is fighting a viral infection, says Todd Rice, M.D., professor of medicine and director of the medical intensive care unit at Vanderbilt Medical Center in Nashville, Tennessee.

Pneumonia is diagnosed with a chest X-ray or CT scan. Your doctor may also send your blood and a mucus sample to a lab for a culture to try to determine what type of bacteria or virus is the culprit.

Pneumonia warning signs and symptoms

Pneumonia symptoms can be mild or severe. They tend to be similar to those of a cold or flu, but they last longer and may get worse over time. Here are some common symptoms.

• Productive cough. You will be “coughing up lots of nasty stuff,” says Charles Bregier, M.D., an emergency medicine physician and medical director at Novant Health in Charlotte, North Carolina. The sputum often has a yellow, green or gray look.  

• Fever. Fever and chills are signs that your body is fighting the infection. But the absence of a fever doesn’t necessarily rule out pneumonia, especially in those age 65 and older.

• Shortness of breath. You may have trouble catching your breath when walking or talking, or feel like you’re breathing faster than normal.

• Chest pain. You may experience sharp or stabbing chest pain that hurts more when you take a deep breath or cough.

• Dizziness or delirium. Some older adults with pneumonia may experience a change in cognition or awareness, says Sarina Sahetya, M.D., a pulmonologist and intensivist at Johns Hopkins Medicine. “If someone comes into the hospital and says their loved one is confused,” she says, “that’s a red flag for us to start looking for infection.”