Authored by Revere Health

Pneumonia: Types, Causes, Symptoms and Prevention

November 15, 2017 | Pulmonology

Pneumonia is an infection that inflames the air sacs in one or both of the lungs, and its symptoms can range from mild to life-threatening. This condition causes air sacs to fill with fluid or pus, causing a cough with phlegm or pus, a fever, chills and difficulty breathing. It can be caused by a variety of factors and is of particular risk for infants, young children and people over 65.

Types and Causes of Pneumonia

Several different germs can cause pneumonia—bacteria and viruses in the air are the most common. In most cases, the body prevents these germs from infecting the lungs. But in others, the germs can overpower the immune system. To help describe what type of pneumonia you have, pneumonia is categorized based on the germs that caused it and where you got it from.

Community-acquired pneumonia is the most common type, occurring outside hospitals or other health facilities. It can be caused by:

  • Bacteria
  • Bacteria-like organisms
  • Fungi (most common in people with chronic health issues or a weakened immune system, or in people who have inhaled large doses of the organisms)
  • Viruses (some of the same viruses that cause the flu or a cold

Other types of pneumonia include:

  • Hospital-acquired pneumonia: Caught during a hospital stay for another illness. Because bacteria causing hospital acquired pneumonia can be more resistant to antibiotics, this type can be serious. People on breathing machines are at higher risk for this type.
  • Healthcare-acquired pneumonia: A bacterial infection in people who live in long-term care facilities or who receive care in outpatient clinics. Kidney dialysis centers are a good example here. Bacteria here can also be more resistant to antibiotics.
  • Aspiration pneumonia: When you inhale food, drink, vomit or saliva into the lungs. This is more likely if something disturbs your normal gag reflex, like a brain injury, swallowing issue or excessive use of alcohol or drugs.

Risk Factors

Anyone can develop pneumonia, but two groups are at the highest risk: children aged 2 years or younger and anyone over the age of 65. Other risk factors include:

  • Being hospitalized (particularly if you’re on a ventilator to help you breathe)
  • Chronic disease: Asthma, chronic obstructive pulmonary disease or heart disease
  • Smoking
  • Weakened or suppressed immune system: People with HIV/AIDS, who have had an organ transplant or who receive chemotherapy or long-term steroids can be at higher risk.

Symptoms and Possible Complications

Symptoms of pneumonia vary depending on the germ that caused them, your age and your overall health. Mild symptoms are similar to a cold or flu, but they last longer. Other signs may include:

  • Chest pain when you breathe or a cough
  • Confusion or changes in mental awareness in adults over 65
  • Cough, often producing phlegm
  • Fatigue
  • Fever, sweating and shaking chills
  • Lower body temperature than normal (in people over 65 or those with weak immune systems)
  • Nausea, vomiting or diarrhea
  • Shortness of breath

In some cases for newborns and infants, no signs are present. In others, they may vomit, have a fever or a cough, appear restless or tired, or have trouble breathing and eating.

If you have trouble breathing, chest pain, a fever over 102 degrees Fahrenheit, a persistent cough or coughing with pus, see your doctor. It’s especially important for high-risk groups to see a doctor if experiencing any symptoms—people over 65 or infants under 2, people with underlying health conditions or a weakened immune system, and people receiving chemotherapy or taking medication to suppress the immune system.

Complications of pneumonia, even with treatment, can include:

  • Bacteremia: A condition in which bacteria enters the bloodstream from the lungs, where it can spread an infection to other organs and cause organ failure.
  • Trouble breathing, possibly requiring hospitalization and use of a ventilator.
  • Pleural effusion: A fluid accumulation in the thin space between layers of tissue that line the lungs and the chest cavity. If this fluid becomes infected, it will have to be drained or removed via surgery.
  • Lung abscess: This can occur if pus forms in the cavity of the lung. Usually treated with antibiotics, lung abscesses can also sometimes be treated with surgery or drainage through a long tube.


Diagnosis and treatment of pneumonia depends on several factors, including age and the cause of the infection. There are also some steps you can take to help prevent pneumonia:

  • •Vaccines: Vaccines can prevent some kinds of pneumonia and the flu. Speak with your doctor about these shots, and remember to review vaccination status even if you think you’ve had this vaccine in the past—standards have changed over time.
  • •Child vaccination: There are different pneumonia vaccines for children under 2, and for children aged 2 to 5 who are at high risk of pneumococcal disease. Children who attend group child care centers should also should get the vaccine, and all children older than 6 months should get a flu vaccine as well.
  • •Hygiene: To prevent respiratory infections that can lead to pneumonia, wash your hands regularly or use an alcohol-based sanitizer.
  • •Smoking: Smoking damages the lungs’ defenses against respiratory infections.
  • •Immune system: Things like proper sleep, regular exercise and a healthy diet all boost the immune system.

If you or your child develops pneumonia, your doctor can offer treatment and tactics for future prevention.



“Pneumonia.” The Mayo Clinic.

“Pneumonia – Topic Overview.” WebMD.


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This information is not intended to replace the advice of a medical professional. You should always consult your doctor before making decisions about your health.