Pneumonia – Symptoms and Causes

ByJanis Updated

Overview

Pneumonia causes inflammation in the air sacs, which can fill with fluid or pus. This leads to symptoms like coughing with phlegm, fever, chills, and breathing difficulties. Different organisms can trigger pneumonia, including:

  • Bacteria
  • Viruses
  • Fungi

The severity of pneumonia varies from mild cases to life-threatening infections. Certain groups face higher risks from pneumonia:

  • Infants and young children
  • Adults over 65
  • People with existing health conditions
  • Individuals with weakened immune systems

These high-risk groups should take extra precautions and seek prompt medical care when symptoms appear.

Symptoms

Mild cases often feel like a cold or the flu, but last longer.

Common symptoms include:

  • Chest pain during breathing or coughing
  • Mental confusion (especially in people over 65)
  • Cough that may produce phlegm
  • Fatigue
  • Fever with sweating and chills
  • Below normal body temperature (in adults over 65 or those with weakened immune systems)
  • Digestive issues like nausea, vomiting, or diarrhea
  • Breathing difficulties

Babies and infants might not show clear signs of pneumonia. They may have vomiting, fever, cough, restlessness, tiredness, or trouble breathing and eating.

When to Seek Medical Help

Visit a doctor if you have:

  • Difficulty breathing
  • Chest pain
  • Fever of 102°F (39°C) or higher that doesn’t go away
  • Persistent cough, especially with pus

People in these high-risk groups should see a doctor promptly:

  • Adults over 65
  • Children under 2 with symptoms
  • People with existing health conditions
  • Those with weakened immune systems
  • Individuals on chemotherapy or immunosuppressive medications

For older adults and people with heart failure or chronic lung problems, pneumonia can become dangerous quickly.

Causes

Pneumonia can develop from various germs that infect the lungs. The most common culprits are bacteria and viruses present in the air we breathe.

While our bodies normally defend against these germs, sometimes they overcome our immune defenses, even in otherwise healthy people.

Community-Acquired Pneumonia

This is the most common form of pneumonia, occurring outside healthcare settings. Several types of organisms can cause it:

  • Bacteria: Streptococcus pneumoniae is the leading bacterial cause of pneumonia in the United States. This infection can develop independently or follow a cold or the flu. It sometimes affects just one section of the lung (lobar pneumonia).

  • Bacteria-like Organisms: Mycoplasma pneumoniae typically causes milder symptoms. This is sometimes called “walking pneumonia” because patients often don’t need bed rest.

  • Fungi: More common in people with ongoing health issues or weakened immune systems. Exposure to large amounts of certain fungi found in soil or bird droppings can cause this type. The specific fungi vary by geographic location.

  • Viruses: Cold and flu viruses can lead to pneumonia. Viruses are the primary cause of illness in children under 5. While usually mild, viral pneumonia can become serious in some cases. COVID-19 has also been linked to severe viral pneumonia.

Hospital-Acquired Pneumonia

Some patients develop pneumonia during hospital stays for other conditions. This form can be particularly dangerous because:

  1. The bacteria may resist antibiotics
  2. Patients are already sick
  3. People on ventilators face a higher risk

Healthcare-Acquired Pneumonia

This bacterial infection affects people in long-term care facilities or those receiving care in outpatient settings, like kidney dialysis centers. Similar to hospital-acquired pneumonia, these bacteria often show greater resistance to antibiotics.

Aspiration Pneumonia

Aspiration pneumonia happens when food, drinks, vomit, or saliva enter the lungs. Risk factors include:

  • Brain injuries
  • Swallowing disorders
  • Excessive alcohol or drug use
  • Any condition that disrupts the normal gag reflex

These conditions can cause substances to enter the lungs instead of the stomach, resulting in infection.

Risk Factors

Children under 2 years old and adults over 65 face the highest risk of pneumonia. However, several other factors can increase your chances:

  • Hospital Stays: People in intensive care units have a higher pneumonia risk, especially those on ventilators.
  • Existing Health Conditions: Having chronic diseases like asthma, COPD, or heart disease makes you more vulnerable.
  • Smoking Habits: Smoking damages the respiratory system’s natural defenses against pneumonia-causing germs.
  • Immune System Issues: A weakened immune system from conditions like HIV/AIDS, organ transplants, chemotherapy, or long-term steroid use significantly increases risk.

Health Problems That May Happen

Pneumonia can lead to several serious health issues, even with proper treatment. People in high-risk groups need to be especially careful.

Infection in the Blood

Bacteria from infected lungs can enter the bloodstream and spread to other body parts. This can damage organs and might lead to organ failure if not treated quickly.

Breathing Problems

Severe pneumonia or existing lung diseases can make it hard to get enough oxygen. Some patients may need hospital care and breathing support from a ventilator while they heal.

Fluid Around the Lungs

Pneumonia sometimes causes fluid to collect between the tissues lining the lungs and the chest cavity. If this fluid gets infected, doctors may need to drain it using a chest tube or surgically remove it.

Lung abscess

An abscess forms when pus collects in a pocket within the lung. Doctors typically treat these with antibiotics. In some cases, they may need to drain the pus using a needle or tube, or perform surgery to remove it.

Ways to Prevent Pneumonia

Getting vaccinated is one of the best ways to prevent pneumonia. Vaccines can protect against certain types of pneumonia and the flu.

Talk to your doctor about which shots you need, as guidelines can change over time. Even if you’ve had a pneumonia vaccine before, you might need an update.

Kids under 2 years old should get a special pneumonia vaccine. Children ages 2–5 who face higher risks should also get vaccinated.

Children in daycare centers should be vaccinated. For children over 6 months, yearly flu shots are recommended.

Maintaining good hygiene is essential for preventing respiratory infections. Wash your hands often, or use alcohol-based hand sanitizer when soap isn’t available.

Other important prevention steps:

  • Don’t smoke, as it damages your lungs’ natural defenses
  • Get enough sleep each night
  • Exercise regularly
  • Eat a balanced, healthy diet

These habits keep your immune system strong. A strong immune system can better fight off infections that could lead to pneumonia.

Health Writer

Janis's areas of expertise include nutrition, exercise, stress management, and mental health. She is passionate about educating and empowering people to take control of their health and make positive changes that can last a lifetime. Janis believes that small, sustainable changes are the key to long-term success, and she works with her clients to develop personalized plans that fit their individual needs and lifestyles.