Pneumonia: Symptoms, Causes, and General Information

Author: Disabled World (DW)
Updated/Revised Date: 31 Jul 2026

Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics

Synopsis

Learn about pneumonia symptoms, causes, diagnosis, and treatment for this lung infection affecting the alveoli and requiring medical evaluation.

At a Glance

• 1 - Viral pneumonia accounts for about 200 million cases each year.
• 2 - As of 2009, pneumonia was the 8th leading cause of death in the United States.
• 3 - Hospital-acquired pneumonia begins at least 72 hours after admission and differs in cause, treatment, and prognosis.
• 4 - The World Health Organization estimates one in three newborn infant deaths is due to pneumonia, and about half are preventable with an available vaccine.

Topic Definition

Pneumonia

Pneumonia is an inflammatory condition of the lung that primarily affects the tiny air sacs called alveoli, where oxygen and carbon dioxide are exchanged. It most often develops from infection with viruses or bacteria, though less common causes include other microorganisms, certain medications, and underlying conditions such as autoimmune diseases. People with pneumonia typically experience a cough, chest pain, fever, and difficulty breathing, and while many cases resolve at home with rest, fluids, and oral antibiotics, the illness can turn serious for older adults, young children, and anyone with a weakened immune system. Because it can progress quickly and remains a leading cause of death worldwide, any suspected case warrants prompt medical evaluation.

Overview

Pneumonia is defined as an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli. It is usually caused by infection with viruses or bacteria and less commonly other microorganisms, certain drugs and other conditions such as autoimmune diseases. Typical symptoms include a cough, chest pain, fever, and difficulty breathing. Before the discovery of antibiotics, one-third of all people who developed pneumonia subsequently died from the infection, however every year, more than 60,000 Americans still die of pneumonia.

Symptoms associated with pneumonia include:

• cough
• chest pain
• fever
• difficulty in breathing

Other possible symptoms are:

• loss of appetite
• fatigue
• blueness of the skin
• nausea
• vomiting
• mood swings
• joint pains or muscle aches

Symptoms of pneumonia need immediate medical evaluation.

For some older adults and people with heart failure or chronic lung problems, pneumonia can quickly become a life-threatening condition. See your doctor if you have difficulty breathing, chest pain, persistent fever of 102 F (39 C) or higher, or persistent cough, especially if you're coughing up pus.

It's especially important that people in these high-risk groups see a doctor:

• Adults older than age 65.
• Children younger than age 2 with signs and symptoms.
• People with an underlying health condition or weakened immune system.
• People receiving chemotherapy or taking medication that suppresses the immune system.

This is a detailed anatomical diagram of the human respiratory system, showing a front view that spans from the nasal cavity at the top to the diaphragm at the bottom. The image illustrates the complete breathing pathway, starting with the nose, nasal structures, and paranasal sinuses, then progressing through the pharynx and larynx (with visible vocal folds and cartilage structures), continuing down the trachea with its characteristic rings, and branching into the main bronchi that lead to both lungs. The lungs are depicted in pink with their internal bronchial tree structure visible in green and purple, showing how airways progressively divide into smaller branches. The right lung displays three lobes (superior, middle, and inferior) separated by fissures, while the left lung shows two lobes with features like the cardiac notch. A detailed inset in the upper right shows the microscopic structure of alveoli, including alveolar sacs, ducts, capillary beds, and blood vessels (pulmonary artery and vein). The orange diaphragm muscle is shown at the base of the lungs, and all major structures are clearly labeled with lines pointing to their respective anatomical features.

Diagnostic tools include x-rays and examination of the sputum. Treatment depends on the cause of pneumonia; bacterial pneumonia is treated with antibiotics. People with infectious pneumonia often have a cough producing greenish or yellow sputum, or phlegm, and a high fever that may be accompanied by shaking chills. Shortness of breath is also common, as is pleuritic chest pain, a sharp, or stabbing pain, either experienced during deep breaths or coughs or worsened by them. People with pneumonia may cough up blood, experience headaches, or develop sweaty and clammy skin.

Most cases of pneumonia can be treated without hospitalization. Typically, oral antibiotics, rest, fluids, and home care are sufficient for complete resolution. However, people with pneumonia who are having trouble breathing, people with other medical problems, and the elderly may need more advanced treatment.

An important test for pneumonia in unclear situations is a chest x-ray. Chest x-rays can reveal areas of opacity (seen as white) which represent consolidation. Pneumonia is not always seen on x-rays, either because the disease is only in its initial stages, or because it involves a part of the lung not easily seen by x-rays.

Chronic obstructive pulmonary disease (COPD) or asthma can present with a polyphonic wheeze, similar to that of pneumonia. Pulmonary edema can be mistaken for pneumonia due to its ability to show a third heart sound and present with an abnormal ECG. Other diseases to be taken into consideration include bronchiectasis, lung cancer and pulmonary emboli.

Hospital-acquired pneumonia, also called nosocomial pneumonia, is pneumonia acquired during or after hospitalization for another illness or procedure with onset at least 72 hrs after admission. The causes, microbiology, treatment, and prognosis are different from those of community-acquired pneumonia. Up to 5% of patients admitted to a hospital for other causes subsequently develop pneumonia. In general, pneumonia is not contagious, but the upper respiratory viruses that lead to it are.

Pneumonia Facts and Statistics

• Viral pneumonia accounts for about 200 million cases.
• Rates are greatest in children less than five, and adults older than 75 years.
• In the United States, as of 2009, pneumonia is the 8th leading cause of death.
• It is a major cause of death among all age groups, resulting in 4 million deaths (7% of the world's total death) yearly.
• Countries with the greatest burden of disease include India (43 million), China (21 million) and Pakistan (10 million).
• Pneumonia is a common illness affecting approximately 450 million people a year and occurring in all parts of the world.
• In 2010, it resulted in 1.3 million deaths, or 18% of all deaths in those under five years, of which 95% occurred in the developing world.
• In 2008, pneumonia occurred in approximately 156 million children (151 million in the developing world and 5 million in the developed world).
• Pneumonia was the most common reason for admission to the hospital after an emergency department visit in the U.S. for infants and children.
• The World Health Organization estimates that one in three newborn infant deaths is due to pneumonia. Approximately half of these deaths can be prevented, as they are caused by the bacteria for which an effective vaccine is available.

Frequently Asked Questions

Is pneumonia contagious from person to person

Pneumonia itself is generally not contagious, but the upper respiratory viruses that can lead to it are spread from person to person.

How long does it take to recover from pneumonia

Recovery varies by person and severity, and many mild cases resolve at home over one to a few weeks with rest, fluids, and prescribed antibiotics, while more serious cases can take longer.

Can you prevent pneumonia with a vaccine

Vaccines are available that protect against some common bacterial causes of pneumonia, and health agencies note that many pneumonia deaths in infants could be prevented through vaccination.

What is the difference between walking pneumonia and regular pneumonia

Walking pneumonia is a milder form that often allows a person to continue daily activities, whereas more severe pneumonia can cause intense symptoms that require rest or hospital care.

Are there different types of pneumonia

Yes, pneumonia is often grouped by where it was acquired and its cause, including community-acquired, hospital-acquired, viral, and bacterial pneumonia.

When should someone go to the emergency room for pneumonia

Seek urgent care for severe difficulty breathing, bluish skin, confusion, chest pain, or a high persistent fever, especially in older adults, young children, and people with weakened immune systems.

Can pneumonia lead to long term lung damage

Most people recover fully, but severe or repeated infections can sometimes cause lasting effects on lung function, particularly in those with existing heart or lung conditions.

Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.

Last updated: 31 Jul 2026