Causes of Pneumonia
Pneumonia is caused by germs that settle in the lungs and multiply, triggering an infection. The air sacs, or alveoli, become inflamed and fill with fluid. The most common causes are bacteria and viruses in the air we breathe, but the body usually prevents these germs from infecting the lungs. When the immune system is overpowered, infection occurs. The main types of infectious agents include:

• Bacteria: The most common cause of bacterial pneumonia in the United States is Streptococcus pneumoniae. This type can occur on its own or after you have had a cold or the flu. Other bacteria like Mycoplasma pneumoniae can cause a milder form of the disease often called walking pneumonia.
• Viruses: The same viruses that cause colds and the flu can cause pneumonia. This is the most common cause of pneumonia in children younger than 5 years. Viral pneumonia is usually mild but can become serious. SARS-CoV-2, the virus that causes COVID-19, also causes pneumonia.
• Fungi: This type is most common in people with chronic health problems or weakened immune systems, and in people who have inhaled large doses of the organisms. The fungi that cause it can be found in soil or bird droppings.
• Aspiration: This occurs when food, drink, vomit, or saliva is inhaled into the lungs. This is more likely if the normal gag reflex is disturbed, such as by a brain injury or excessive alcohol use.

Risk Factors
Anyone can get pneumonia, but certain factors increase the risk of developing the infection or experiencing more severe symptoms. High-risk groups include children who are 2 years old or younger and people who are age 65 or older. Other risk factors include:

• Hospitalization: You remain at greater risk of pneumonia if you are in a hospital intensive care unit, especially if you are on a machine that helps you breathe.
• Chronic disease: You are more likely to get pneumonia if you have asthma, chronic obstructive pulmonary disease (COPD), or heart disease.
• Smoking: Smoking damages the body's natural defenses against the bacteria and viruses that cause pneumonia.
• Weakened or suppressed immune system: People who have HIV/AIDS, have had an organ transplant, or who receive chemotherapy or long-term steroids are at risk.

Prevention
Preventing pneumonia involves a combination of vaccination, good hygiene, and healthy lifestyle choices. Vaccines are available to prevent some types of pneumonia and the flu. Vaccination guidelines change over time so it is important to review vaccination status with a doctor. The pneumococcal vaccine is recommended for children under age 2 and adults over age 65. Primary prevention steps include:

• Get vaccinated: Shots are available for pneumococcal pneumonia, influenza, and COVID-19.
• Practice good hygiene: Wash hands regularly or use an alcohol-based hand sanitizer to protect against respiratory infections.
• Don't smoke: Tobacco use damages the lungs' ability to fight off infection.
• Keep your immune system strong: Get enough sleep, exercise regularly, and eat a healthy diet.

Signs and Symptoms
The signs and symptoms of pneumonia vary from mild to severe, depending on factors such as the type of germ causing the infection, and the patient's age and overall health. Mild signs and symptoms are often similar to those of a cold or flu, but they last longer. Common symptoms include:

• Chest pain when breathing or coughing.
• Confusion or changes in mental awareness (in adults age 65 and older).
• Cough, which may produce phlegm.
• Fatigue.
• Fever, sweating, and shaking chills.
• Lower than normal body temperature (in adults older than age 65 and people with weak immune systems).
• Nausea, vomiting, or diarrhea.
• Shortness of breath.

Symptoms in Children and Newborns
Newborns and infants may not show any sign of the infection. Or they may vomit, have a fever and cough, appear restless or tired and without energy, or have difficulty breathing and eating. Parents should watch for rapid breathing or grunting sounds while the child breathes.

How Pneumonia Is Diagnosed
Doctors typically start with a medical history and physical exam. During the exam, the doctor will listen to the lungs with a stethoscope to check for abnormal bubbling or crackling sounds that suggest inflammation or fluid. If pneumonia is suspected, the following tests may be ordered to confirm the diagnosis and identify the cause:

• Chest X-ray: This helps diagnose pneumonia and determine the extent and location of the infection. However, it cannot tell the doctor what kind of germ is causing the pneumonia.
• Blood tests: These are used to confirm an infection and to try to identify the type of organism causing the infection. However, precise identification is not always possible.
• Pulse oximetry: This measures the oxygen level in the blood. Pneumonia can prevent the lungs from moving enough oxygen into the bloodstream.
• Sputum test: A sample of fluid from the lungs (sputum) is taken after a deep cough and analyzed to help pinpoint the cause of the infection.

Additional Testing for High-Risk Patients
If a patient is older than 65, in the hospital, or has serious symptoms or health conditions, the doctor might recommend a CT scan to get a better look at the lungs or a pleural fluid culture, which involves taking a fluid sample from the pleural space to determine the type of infection.

Differential Diagnosis
Because the symptoms overlap with other respiratory conditions, pneumonia can be confused with bronchitis, asthma, chronic obstructive pulmonary disease (COPD) exacerbations, or heart failure. Proper diagnostic imaging and lab work help distinguish pneumonia from these other conditions.

Medical Treatments
Treatment for pneumonia depends on the type of pneumonia, the severity of the infection, and general health. The goal is to cure the infection and prevent complications. Specific treatments include:

• Antibiotics: These are used to treat bacterial pneumonia. It may take time to identify the type of bacteria and choose the best antibiotic. Symptoms often improve within a few days, but the medication must be taken until completion to prevent recurrence.
• Cough medicine: This may be used to calm a cough so that rest is possible. Since coughing helps loosen and move fluid from the lungs, it is generally a good idea not to eliminate the cough completely.
• Fever reducers/pain relievers: Medications such as aspirin, ibuprofen, or acetaminophen are taken as needed for fever and discomfort.

Viral and Fungal Pneumonia Management
Antibiotics do not work on viruses. Viral pneumonia usually improves with supportive care, although doctors may prescribe antiviral medication for specific viruses like influenza or COVID-19. Fungal pneumonia is treated with antifungal medications, which may need to be taken for several weeks to clear the infection.

Hospitalization and Procedures
Hospitalization may be required if symptoms are severe or if the patient is at high risk due to age or other health conditions. In the hospital, treatments often include:

• Intravenous (IV) fluids to prevent dehydration.
• Oxygen therapy to maintain oxygen levels in the bloodstream.
• Breathing treatments to help open airways.
• Ventilator support in severe cases where the patient cannot breathe adequately on their own.

Lifestyle and Home Management
Recovering from pneumonia requires time and rest. It is important to stay home from school or work until the temperature returns to normal and the coughing stops. Drinking plenty of fluids helps loosen the mucous in the lungs. Patients should avoid smoke to let the lungs heal. A humidifier may also help keep the air moist and soothe irritated lungs.

When to Seek Medical Care
See a doctor if you have difficulty breathing, chest pain, persistent fever of 102 F (39 C) or higher, or persistent cough, especially if you are coughing up pus. It is especially important that people in high-risk groups see a doctor. Seek emergency care immediately if you experience:

• Severe difficulty breathing or inability to catch your breath.
• Blue color in the lips or fingertips.
• New confusion or difficulty waking up.
• Severe chest pain.

Severity and Course
Pneumonia severity ranges from mild to life-threatening. "Walking pneumonia" is a mild form that may not require bed rest, while severe pneumonia involves extensive lung inflammation and respiratory distress. The condition is usually acute, with the infection clearing up in one to three weeks with treatment. However, fatigue can persist for a month or more. The course of the disease depends heavily on the causative agent (bacterial vs. viral) and the patient's immune response.

Complications
Even with treatment, some people with pneumonia, especially those in high-risk groups, may experience complications. These can include:

• Bacteremia: Bacteria from the lungs entering the bloodstream can spread the infection to other organs, potentially causing organ failure.
• Difficulty breathing: Severe pneumonia can make it hard to breathe in enough oxygen, requiring hospitalization and use of a breathing machine.
• Pleural effusion: Pneumonia may cause fluid to build up in the thin space between layers of tissue that line the lungs and chest cavity (pleura). If the fluid becomes infected, it may need to be drained through surgery or with a needle.
• Lung abscess: An abscess occurs if pus forms in a cavity in the lung. This is usually treated with antibiotics, but sometimes requires drainage or surgery.

Prognosis and Life Expectancy
The outlook for pneumonia is generally good for healthy younger adults who receive prompt treatment. For these individuals, life expectancy is typically not affected. However, pneumonia is a leading cause of death in children under five and adults over 65 worldwide. Prognosis worsens with age, the presence of comorbidities like heart or lung disease, and hospitalization. Early diagnosis and modern antibiotics have significantly improved survival rates compared to the past, but it remains a serious medical condition for vulnerable populations.

Impact on Daily Activities
During the acute phase of pneumonia, normal daily activities are often impossible due to extreme fatigue, shortness of breath, and fever. Patients typically need to take time off from work or school to rest and recover. Even after the infection clears, it is common to feel tired for several weeks. Physical stamina may be reduced, meaning that returning to exercise or strenuous work should be done gradually. Listen to your body and do not rush the recovery process.

Coping and Support
Support from family or friends is helpful for daily tasks like cooking or shopping while energy levels are low. Emotional support can also be beneficial, especially for older adults who may feel isolated during recovery. Maintaining good nutrition and hydration is a practical strategy to support the immune system during this time.

Questions to Ask Your Healthcare Provider
Preparing questions for doctor appointments can help clarify the diagnosis and treatment plan. Consider asking:

• What is the likely cause of my pneumonia (bacterial, viral, or other)?
• Is my type of pneumonia contagious, and how can I protect my family?
• What specific signs should I look for that indicate my condition is getting worse?
• Do I need a follow-up chest X-ray to ensure the infection has cleared?
• Are there vaccines I should get after I recover to prevent this from happening again?
• When can I safely return to work, school, or my exercise routine?

Q: Is pneumonia contagious?
A: Pneumonia itself is not contagious, but the germs that cause it are. The viruses and bacteria that lead to pneumonia can spread from person to person through coughs, sneezes, or touching contaminated surfaces. However, being exposed to these germs does not guarantee you will develop pneumonia; it might result in a cold or flu instead.

Q: What is the difference between viral and bacterial pneumonia?
A: Bacterial pneumonia is caused by bacteria and is treated with antibiotics. It often causes more severe symptoms. Viral pneumonia is caused by viruses and cannot be treated with antibiotics; it typically resolves with supportive care and rest, though antiviral medications are sometimes used. Your doctor can determine the type through testing.

Q: What is walking pneumonia?
A: Walking pneumonia is a non-medical term for a mild case of pneumonia. It is often caused by the bacteria Mycoplasma pneumoniae. People with this form of the condition may not feel sick enough to stay in bed or go to the hospital and can often continue their daily activities, hence the name.

Q: Can I get pneumonia from going outside with wet hair or being in the cold?
A: No, cold weather or wet hair does not cause pneumonia. Pneumonia is an infection caused by bacteria, viruses, or fungi. However, cold and flu viruses do circulate more commonly in the winter, and having the flu can increase the risk of developing secondary pneumonia.

Q: How long does it take to recover from pneumonia?
A: Recovery time varies. Most people see an improvement in symptoms within a few days of starting treatment. However, the feeling of tiredness and fatigue can linger for a month or more. Complete recovery may take several weeks, and it is important to rest during this time.