Pneumonia is an infection of the lungs that causes inflammation in one or both lungs. The infection can affect the tiny air sacs called alveoli, which normally fill with air when a person breathes. During pneumonia, these air sacs may fill with fluid or pus, making it harder for the lungs to exchange oxygen properly.
Pneumonia can be caused by different types of microorganisms, including bacteria, viruses, and fungi. Bacterial pneumonia is a common type, while viral pneumonia can occur with infections such as influenza and COVID-19. The specific cause may depend on a person's age, health, immune system, environment, and recent infections.
Pneumonia can range from a mild illness to a serious and potentially life-threatening condition. Healthy adults may recover with appropriate treatment, while babies, older adults, people with chronic diseases, and individuals with weakened immune systems may be at greater risk of complications.
Common symptoms of pneumonia include cough, fever, chills, shortness of breath, chest pain, fatigue, and mucus production. Some people may also experience nausea, vomiting, headache, or confusion.
Pneumonia can develop after another respiratory infection or may occur when bacteria or viruses enter the lungs directly. In some cases, food, liquid, saliva, or stomach contents can enter the lungs, causing aspiration pneumonia.
Doctors diagnose pneumonia based on symptoms, physical examination, oxygen levels, and sometimes a chest X-ray or other imaging tests. Blood tests and tests of mucus or respiratory samples may help identify the cause in certain cases.
Treatment depends on the cause and severity of the infection. Bacterial pneumonia may require antibiotics, while antibiotics do not work against viral pneumonia. Severe cases may require hospitalization, oxygen therapy, intravenous medicines, and other supportive treatment.
Vaccination, hand hygiene, avoiding smoking, maintaining good general health, and managing chronic conditions can help reduce the risk of pneumonia.
Pneumonia can be caused by several types of microorganisms.
Bacteria are a common cause of pneumonia. Streptococcus pneumoniae is an important bacterial cause, although many other bacteria can also cause lung infections.
Viral pneumonia can be caused by respiratory viruses such as influenza viruses, respiratory syncytial virus (RSV), and SARS-CoV-2, the virus that causes COVID-19.
Fungal pneumonia is less common and is more likely to affect people with weakened immune systems or certain environmental exposures.
Pneumonia can also develop through aspiration. This occurs when food, liquid, saliva, or stomach contents accidentally enter the lungs instead of going into the digestive system.
People with swallowing problems, certain neurological conditions, reduced consciousness, or severe acid reflux may have an increased risk of aspiration pneumonia.
Pneumonia may develop after another respiratory infection because the lungs and airways become more vulnerable to additional infection.
The risk of pneumonia increases with age. Babies and young children are also more vulnerable because their immune and respiratory systems are still developing.
People with chronic conditions such as asthma, COPD, diabetes, heart disease, or kidney disease may have a higher risk of severe pneumonia.
Smoking damages the natural defenses of the respiratory system and increases the risk of lung infections.
Heavy alcohol consumption can also increase pneumonia risk by affecting immune function and increasing the risk of aspiration.
People with weakened immune systems, including those receiving certain cancer treatments or immune-suppressing medicines, may be more susceptible to serious pneumonia.
Some types of pneumonia can spread from person to person through respiratory droplets or aerosols, while others are caused by microorganisms already present in the environment or the person's own body.
Pneumonia itself is not always contagious. Whether it can spread depends on the microorganism causing it.
Several steps can help reduce the risk of pneumonia.
Vaccination is one of the most effective preventive measures. Vaccines are available against several infections that can cause pneumonia, including pneumococcal disease, influenza, COVID-19, and certain other respiratory infections.
The appropriate vaccines depend on age, health conditions, pregnancy status, and local recommendations.
Regular hand washing can reduce the spread of respiratory viruses and bacteria.
Avoid touching the eyes, nose, and mouth with unwashed hands.
Cover coughs and sneezes with a tissue or the elbow and dispose of used tissues properly.
Avoid close contact with people who have contagious respiratory infections when possible.
Improving ventilation in indoor spaces can reduce exposure to respiratory infectious particles.
Do not smoke. Smoking damages the lungs' natural defense mechanisms and significantly increases the risk of pneumonia and other respiratory diseases.
People who smoke should consider quitting to improve lung health.
Avoiding secondhand smoke is also important.
Managing chronic conditions such as diabetes, asthma, COPD, heart disease, and kidney disease can reduce the risk of serious respiratory infections.
Maintaining a balanced diet, getting adequate sleep, and staying physically active can support general immune and respiratory health.
For people at risk of aspiration pneumonia, medical evaluation of swallowing problems may be helpful.
Keeping the head elevated during and after meals may be recommended for some people with swallowing or reflux-related risks.
Older adults and people with weakened immune systems should seek medical advice promptly when symptoms of a serious respiratory infection develop.
Pneumonia is a potentially serious lung infection, but many cases can be successfully treated, especially when diagnosed early.
A persistent cough, fever, shortness of breath, chest pain, or worsening weakness should not be ignored. People with severe breathing difficulty, bluish lips, confusion, fainting, or very low oxygen levels need urgent medical care.
Preventive measures such as vaccination, hand hygiene, avoiding smoking, managing chronic diseases, and reducing exposure to respiratory infections can lower the risk of pneumonia.
The most appropriate treatment depends on the underlying cause. Bacterial pneumonia may require antibiotics, while viral pneumonia is generally managed with supportive care and, in selected cases, antiviral medicines.
With timely diagnosis, appropriate treatment, and careful monitoring, most people recover from pneumonia. However, severe infection can lead to complications such as respiratory failure, bloodstream infection, or other organ problems, making early medical attention especially important for people at higher risk.
Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider. In an emergency, call emergency services immediately.