Pneumonia is a lung infection most commonly caused by bacteria or viruses and less so by fungal infections or aspiration (inhaling a substance into the lungs). Pneumonia leads to airway inflammation, and the alveoli (air sacs) may fill with fluid.

Even mild cases of pneumonia have the potential to cause complications, so no occurrence should be taken lightly. The severity of symptoms can range from mild to life-threatening.

This article will discuss the complications of pneumonia and the importance of prevention, early diagnosis, and prompt treatment.

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Complications of Pneumonia

This section provides examples of possible complications of pneumonia. It's important to note that most of the below complications require chest imaging to diagnose.

Pleural Effusion

A pleural effusion is a buildup of fluid between the lung and chest wall. It can be caused by an infection due to a virus, pneumonia, or heart failure.

Outside the lungs, pneumonia causes a buildup of exudative fluid—a watery discharge that is caused by tissue leakage due to inflammation or local cellular damage. 

Pleural effusion usually results from bacterial pneumonia, although any type of pneumonia can cause this to form. Symptoms include:

  • Fever
  • Chest pain
  • Dry cough
  • Shortness of breath
  • Orthopnea, or shortness of breath when lying down

If a pleural effusion results from pneumonia, your healthcare provider may also watch for the potential development of an empyema, a collection of pus in the space between the chest wall and lungs called the pleural cavity.

Collapsed Lung

Clinically known as a pneumothorax, a collapsed lung is a rare complication of pneumonia. In a collapsed lung, air escapes the lung and gets trapped in the pleural cavity, resulting in an increase in pressure that hinders the lung's ability to expand and fill with air when you take a breath.

A tall, thin person is at the highest risk of a collapsed lung but anyone can develop this condition, especially if they have pneumonia.

Symptoms include:

  • Fast breathing
  • Racing heartbeat
  • Shortness of breath
  • Fatigue
  • Chest pain on deep breathing (usually on one side of the chest)

Respiratory Failure

To survive, you need to take oxygen into your lungs and breathe out carbon dioxide. Any condition that compromises your ability to do so can lead to respiratory failure, a life-threatening condition that develops when the lungs can’t get enough oxygen into the blood.

The inflammation and infections that cause pneumonia can injure the lungs, slowing oxygen delivery to vital tissues and causing carbon dioxide to build up, damaging the tissues and organs.

Respiratory failure is a medical emergency. It can happen suddenly or over a long period of time. If you have pneumonia and experience any of these symptoms, seek immediate medical attention:

  • Extreme fatigue
  • Confusion
  • Feeling like you can’t get enough air
  • Lips or fingers that turn blue
  • Peripheral pulse oximetry reading consistently lower than 90%

Lung Abscess

Pneumonia is one of the leading causes of a primary lung abscess, a death of the lung tissue that leads to the formation of pus-filled cavities. The formation of one or multiple small (less than 2 centimeters) abscesses is occasionally referred to as necrotizing pneumonia.

Lung abscess commonly presents with:

  • Fever
  • Chest pain
  • Foul-smelling productive cough that includes green, brown, or blood-tinged sputum

Renal Failure

Studies show that pneumonia puts you at increased risk of chronic kidney disease (CKD), and CKD can cause pneumonia.

The bacteria that cause pneumonia can get into the bloodstream, infecting your kidneys and several other organs along the way, while chronic kidney disease can weaken your immune system making you vulnerable to opportunistic infections.

Renal failure is much more likely in those with bacteremia or respiratory failure because the kidneys are not getting enough blood—and therefore oxygen—to perform their job.

Bacteremia and Sepsis

Bacterial infections are the most common cause of the life-threatening medical emergency sepsis.

Bacteremia is the presence of viable bacteria in the circulating blood and a major cause of sepsis. Sepsis is systemic (body-wide) organ failure as a result of bacterial infection. Bacteria should never be present in the blood. When this occurs the body works hard to eliminate the infection from the bloodstream. During the process, the body can start to damage its own organs.

Pneumonia that is complicated by bacteremia and sepsis can cause damage to the kidneys, liver, and heart.

The stress of your illness and compromised pulmonary functions means the body is not getting the oxygen it desperately needs. Over time this can lead to permanent organ damage and even death. Damage to any of these three organs can present as:

  • Swelling in your feet, ankles, legs, or stomach
  • Fatigue
  • Loss of appetite
  • Nausea
  • Weight loss
  • Sudden weight gain
  • Confusion
  • Weakness

Risk Factors for Pneumonia Complications

There are factors that put someone at a greater risk for experiencing pneumonia complications. These risks are outlined below.


Pneumonia has a high prevalence in very young children and very old adults. To be clear, pneumonia can affect anyone at any age, but the two age groups with the highest prevalence, both for contracting it and for having more severe cases, are children under 2 years old and adults 65 years old and over.

Being Hospitalized

People in the hospital are often very sick and cannot fight off germs, so they are vulnerable to hospital-acquired pneumonia, which tends to be caused by organisms that are far more deadly and more resistant to treatment than those found in the community.

The germs that cause pneumonia in the hospital can also spread quickly from healthcare workers who pass them off to patients and each other (and vice versa) from their hands, clothes, or the instruments they use. This underscores the importance of handwashing, wearing protective gowns, and taking other safety measures. 

Of note, people on a respirator or ventilator—those who are unconscious or in a coma—and those who cannot feed themselves are not only more prone to hospital-acquired pneumonia but also aspiration pneumonia


Smoking cigarettes can damage the lungs, leaving them vulnerable to infections from bacteria, viruses, and fungi. 

Being Immunocompromised

If you have a medical condition that weakens the immune system like human immunodeficiency virus (HIV), diabetes, and cancer; use steroids long-term (especially to manage autoimmune diseases or after organ transplantation); or experience functional and natural declines in your immune system as you age, you are more vulnerable to even relatively harmless germs. This is because under certain conditions your body’s natural defense system becomes compromised.

Therefore, the best ways to strengthen your immune system are to manage any underlying conditions you may have, stay active, keep your weight within a healthy range, and lead a generally healthy lifestyle that includes eating a balanced diet, not smoking, and drinking little to no alcohol.

Chronic Disease

You're more likely to get pneumonia if you have a chronic respiratory condition like asthma or chronic obstructive pulmonary disease (COPD), diabetes, or heart disease. Individuals with one or more of these conditions are at increased risk of developing community-acquired pneumococcal disease compared with those without these conditions. Therefore, the need to get the pneumonia vaccine is important in people with chronic respiratory conditions.

Preventing Complications of Pneumonia

Get Vaccinated

Vaccines help prevent pneumonia by boosting your immunity against some of the common bacteria and viruses that cause illness. Getting all of the following vaccines can safeguard you against pneumonia:

Vaccines are incredibly safe and effective, but they can have side effects. Speak to a healthcare provider so you know what to expect with each vaccine.

Of note, the Centers for Disease Control and Prevention (CDC) recommends that infants younger than 2 years old take four doses of the pneumonia shot. These would be given at two months, four months, and six months old. They should also get a booster between 12 and 15 months. Adults age 65 years old and older should get vaccines that help prevent bacterial pneumonia.

Streptococcus pneumoniae, often simply referred to pneumococcus, is a common bacterium that can cause serious lung infections like pneumonia. In older adults, it may be deadly because it can cause invasive infections in the tissues covering the brain and spinal cord (meningitis). Studies have shown that the risk of pneumonia is decreased by 50 to 80% in this group after taking two rounds of the pneumonia vaccine. The two shots provide immunity for the rest of your life in those who remain generally healthy.

The CDC has also updated its guidelines to indicate that adults 65 years and older may need only one of these vaccines, but they are still eligible for both.

Practice Good Hygiene

One of the best ways to prevent respiratory infections is to practice proper hygiene. Some useful techniques include:

  • Washing your hands regularly, with soap and warm water for at least 20 seconds
  • Cleaning and disinfecting surfaces that are touched a lot (with alcohol-based products)
  • Coughing or sneezing into a tissue or into your elbow or sleeve
  • Limiting contact with cigarette smoke or quitting smoking
  • Properly caring for conditions, such as asthma, diabetes, or heart disease
  • Avoiding any at-risk or immunocompromised friends or family when you are sick

Don’t Smoke

The chemicals in cigarettes can compromise the immune system, lowering its ability to defend you from the organisms that make you sick. Never smoking or quitting if you do smoke are effective ways to lower your pneumonia risk.

Boost Your Immune System

Many products on the market promise to boost your immune system and safeguard you from disease-causing germs in the environment. However, boosting your immune system is less about taking natural herbs and over-the-counter (OTC) medications and more about living as healthy a lifestyle as possible.

Your immune system is most efficient when protected from environmental hazards. It may help to do the following:

  • Don't smoke.
  • Drink alcohol in moderation.
  • Eat a diet high in fruits and vegetables.
  • Exercise regularly.
  • Maintain a healthy weight.
  • Get adequate sleep.
  • Take steps to avoid infection, such as washing your hands frequently and cooking meats thoroughly.
  • Minimize stress.
  • Keep current with all recommended vaccines, which prime your immune system to fight off infections when they enter your body.
  • Cover up and consider wearing a mask when it’s cold outside, as influenza—a major trigger of pneumonia—lingers in the air for longer periods of time in cold air.


Pneumonia is a lung infection that can lead to a variety of health complications including pleural effusion, lung abscess, organ and respiratory failure, and sepsis, especially if left untreated. 

A Word From Verywell

Prevention is the single best way to avoid medical complications from pneumonia. Practicing proper hygiene, getting vaccinated, and living a healthy lifestyle can help you avoid life-threatening conditions.

Frequently Asked Questions

  • What is the most common complication of pneumonia?

    Acute respiratory distress (ARDS) and respiratory failure are the most common complications of serious pneumonia.

  • Can pneumonia damage lungs?

    Yes, pneumonia can damage the lungs and cause a myriad of complications, including exudative pleural effusions, pneumothorax, and a compromised ability to oxygenate the blood, which can lead to systemic organ failure.

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