Pneumonia
Pneumonia is an infection in one or both lungs that inflames the air sacs, which may fill with fluid or pus and make breathing harder.
What pneumonia is
Pneumonia is a lung infection that causes inflammation in the tiny air sacs where oxygen normally passes into the blood. The air sacs can fill with fluid, pus, and immune cells, making it harder to breathe and harder for the lungs to exchange oxygen. Pneumonia can affect one area of one lung or involve both lungs.
Causes
Many germs can cause pneumonia. Bacteria, viruses, and fungi are the main groups, and the likely cause can depend on age, vaccination history, immune function, location, exposures, and whether the infection began in the community or during healthcare. Antibiotics help bacterial pneumonia, but they do not treat viral pneumonia unless a bacterial infection is also present.
Symptoms
Common symptoms include cough, fever, chills, shortness of breath, chest pain that may worsen with breathing or coughing, fatigue, and mucus production. Older adults may have confusion or lower-than-normal temperature. Infants may feed poorly, breathe fast, seem unusually tired, or show chest retractions when breathing.
Risk factors
Risk is higher for very young children, older adults, smokers, people with COPD, asthma, heart disease, diabetes, kidney disease, weakened immune systems, swallowing problems, recent viral infections, or recent hospitalization. Crowded settings and exposure to smoke or air pollution can also make respiratory infections more likely or more severe.
Diagnosis
Clinicians diagnose pneumonia using symptoms, vital signs, lung exam, oxygen levels, and sometimes chest X-ray. Blood tests, sputum tests, viral tests, blood cultures, or CT imaging may be used when illness is severe, the cause is unclear, or the person has higher risk. Imaging can show lung opacities, but results must be interpreted with the clinical picture.
Treatment
Treatment depends on the likely germ, severity, age, and other health conditions. Bacterial pneumonia may be treated with antibiotics. Viral pneumonia may require supportive care and sometimes antiviral medicine. Severe cases may need oxygen, intravenous fluids, hospitalization, breathing support, or treatment of complications such as fluid around the lung.
Prevention
Prevention includes recommended vaccines, such as pneumococcal, flu, COVID-19, RSV, and Hib vaccines for people who are eligible. Handwashing, staying away from smoke, improving indoor air, managing chronic lung or heart disease, safer swallowing care when needed, and responsible antibiotic use can all reduce risk or complications.
Why it matters
Pneumonia matters because it sits at the crossroads of infection, lung health, vaccination, antibiotics, aging, and air quality. It can turn serious quickly in vulnerable people, yet many risks can be lowered through prevention, early recognition, and the right treatment for the actual cause.