Pneumonia

Pneumonia is an inflammatory disease of the lung parenchyma caused by infection that leads to alveolar filling with fluid and inflammatory cells. It can result from bacteria, viruses, fungi, or parasites, and may follow aspiration or inhalation of infectious material. Pneumonia affects one or both lungs and can range from mild to life-threatening.

Common symptoms include cough, fever, chills, shortness of breath, chest pain, and fatigue. Sputum production may be yellow or green, and confusion or low oxygen levels can occur, especially in older adults or people with chronic illnesses. Physical examination may reveal crackles and reduced breath sounds. Diagnosis combines clinical assessment with imaging and laboratory tests. A chest X-ray is typical, but computed tomography may be used in uncertain cases. Blood tests, sputum cultures, and urinary or blood antigen tests help identify the cause, though many cases are treated empirically based on severity and local guidelines.

Treatment depends on the likely cause and severity. Bacterial pneumonia is usually treated with antibiotics, chosen according to guidelines and resistance patterns. Viral pneumonia may require antiviral therapy and supportive care. Hospitalization is considered for severe cases, older patients, or those with comorbidities. Supportive care includes oxygen therapy, fluids, and pain control. Potential complications include pleural effusion, empyema, sepsis, and acute respiratory failure.

Prevention emphasizes vaccination (pneumococcal and influenza vaccines), good hand hygiene, smoking cessation, and managing risk factors such as aspiration. Most people recover with appropriate treatment, though outcomes vary by age and underlying health.