Pneumonia Overview

You might brush off a dry or phlegmy cough as the common cold or seasonal flu. Pneumonia can look like other infections early on, but make no mistake: it can quickly become life-threatening, especially for young children, adults over 65, and people with weak immune systems. Treatment varies depending on the type of pneumonia and its severity.

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Pneumonia is when one or both of your lungs becomes infected. Although the condition can be life threatening, most people do recover with the proper treatment. Certain people are more at risk for developing pneumonia, but you can help prevent it by not smoking, taking care of yourself, and staying away from people who are sick.

What Is It

Pneumonia is when the air sacs in your lung become infected. They then become inflamed and fill with pus and other fluids. Pneumonia can be either lobular, which is when one or both of the lobes of the lung are infected, or bronchial, which affects patches in both lobes.

Anyone can get pneumonia, but small children and infants, people older than 65, pregnant women, smokers, people exposed to secondhand smoke or other environmental toxins, people who are hospitalized, and people with chronic health issues like heart or lung disease and weakened immune systems are most at risk for more severe illness.


There are several different types of pneumonia, depending on the underlying cause, where you acquire the infection, and which part of your respiratory system is affected.

The most common type of pneumonia is bacterial pneumonia, which can also be the most serious. This frequently only affects one lobe and is more likely to strike people who already have a respiratory disease or virus or because they've just had surgery. While mycoplasma pneumonia, also called "walking pneumonia," is also bacterial, it's often put in a separate category because the symptoms can be different.

Viruses can also cause pneumonia (called viral pneumonia), the most common being the influenza virus. In young children, the most common cause of viral pneumonia is respiratory syncytial virus (RSV).

Sometimes doctors categorize pneumonia by where it was acquired. For instance, hospital-acquired pneumonia develops when you are hospitalized for another condition. These infections can be more serious because the bacteria are often resistant to antibiotics. Healthcare-acquired pneumonia spreads in long-term facilities or outpatient sites like dialysis centers. Community-acquired pneumonia is transmitted out in the community.

Experts often also refer to two other types of pneumonia: ventilator-associated pneumonia, which develops when someone is on a ventilator, and aspiration pneumonia, when you inhale something—food, drink, vomit, or saliva—into your lungs. Typically, this affects people who have had a stroke or another condition that can interfere with the gag reflex.


The various types of pneumonia can involve slightly different symptoms. For instance, bacterial pneumonia can appear suddenly or gradually, while viral pneumonia usually takes a few days after infection to show up. Symptoms of mycoplasma pneumonia may take a week or more and more often affects people younger than 40.

In the early stage of pneumonia, symptoms mimic those of the flu or a cold: fever, shortness of breath, cough, muscle aches and pains, and weakness—but pneumonia lasts longer than either a cold or the flu and can also cause:

People over 65 may actually have a lower-than-normal temperature, while the fever accompanying mycoplasma pneumonia can be quite high. Small children and babies can be tired or restless and they're more likely to have vomiting than adults.

See your doctor if you have a fever of 102 degrees or higher or a cough that doesn't go away. You may also want to check in with a health care professional if you're in a high-risk group.

If pneumonia isn't treated, it can lead to complications, such as:

  • Bacteremia. This is when bacteria crosses into the bloodstream, which can lead to septic shock or organ failure.
  • Abscesses in your lungs. These are pockets of pus in your lungs which can cause the lung tissue to die.
  • Pleural disorders, when fluid fills the tissue between your lungs and your chest cavity. The pleura is the tissue that covers the outside of the lungs and lines the inside of your chest cavity. This may need to be drained.
  • Kidney failure.
  • Acute Respiratory Distress Syndrome, when fluid enters the lung.
  • Respiratory failure.
  • Liver, kidney or heart damage.


Bacterial pneumonia is caused by bacteria which live in the environment around us, the most common being Streptococcus pneumoniae. This infects more than 900,000 Americans annually. Other bacteria which can cause pneumonia are Legionella pneumophilia (Legionnaires' disease), Chlamydia pneumoniae, and Haemophilus influenzae, which, surprisingly, doesn't actually cause the flu. Common cold viruses, flu viruses, respiratory syncytial virus (RSV), and SARS-CoV-2 (responsible for Covid-19) all can cause viral pneumonia. The type of fungi that can give rise to pneumonia include Pneumocystis jirovecii, Coccidioidomycosis, and Histoplasmosis. These are found in soil and bird droppings.


Diagnosing pneumonia is a balancing act, as so many symptoms overlap with other respiratory conditions. Doctors usually start with a medical history to find out how long you've had symptoms, if you've been sick with another illness, and if you smoke. Next is a physical exam, when the doctor assesses your vital signs and will listen to your lungs with a stethoscope. After that, your doctor may decide to do blood or sputum tests to identify the organism causing the pneumonia, a chest X-ray to discern the condition of your lungs, and an arterial blood gas test to gauge the amount of oxygen in your vessels.


Treatment depends on what type of pneumonia you have and how severe the symptoms are. Most cases of pneumonia are mild and can be treated at home with over-the-counter medications. Aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen or ibuprofen can help lower your fever. Try not to take any cough remedies as coughing is your body's natural way to clear your lungs.

Doctors often treat bacterial pneumonia with antibiotics and some cases of viral pneumonia with antivirals. People who are hospitalized may also need intravenous fluids, oxygen therapy, and even a ventilator to help them breathe. Be patient about your recovery. Some people feel tired for weeks after the actual infection has resolved.


The best way to prevent pneumonia is to get one of two pneumonia vaccines that are available for both adults and children. You should also make sure you have all your other vaccinations up to date to prevent diseases that could lead to pneumonia. This includes your annual flu shot as well as pertussis (whooping cough), chicken pox, and measles. Children should get the Hib vaccine can help prevent pneumonia from Haemophilus influenza type b. Doctors sometimes prescribe prophylactic antibiotics to people with weakened immune systems and a drug called Synagis (palivizumab) to children younger than two to stave off pneumonia from RSV.

Here are other precautions you can take:

  • Wash your hands often with soap and water or an alcohol-based hand sanitizer.
  • Sanitize high touch surfaces like doorknobs and counters.
  • Stay away from people who are sick.
  • Don't smoke.
  • Take care of your overall health by getting enough sleep, exercising, and following a healthy diet.
  • Make sure other medical conditions are being treated.

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