Pneumonia: Complete Guide to Symptoms, Causes, and Treatment
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Pneumonia: Complete Guide to Symptoms, Causes, and Treatment
TL;DR
Pneumonia is an infection that inflames the air sacs in one or both lungs, which may fill with fluid or pus. It can range from mild to life-threatening and is most serious for infants, older adults, and people with weakened immune systems or other health problems. Treatment depends on the type and severity, ranging from antibiotics and home care to hospitalization.
Quick Answer
Pneumonia is an infection that causes inflammation in the air sacs of one or both lungs, which can fill with fluid or pus, causing cough, fever, chills, and difficulty breathing. It can be caused by bacteria, viruses, or fungi, and severity ranges from mild to life-threatening. Treatment typically involves antibiotics for bacterial pneumonia, along with rest, fluids, and fever-reducing medications; severe cases may require hospitalization.
What Is Pneumonia?
Pneumonia is an infection that inflames the air sacs (alveoli) in one or both lungs. The air sacs may fill with fluid or pus, causing symptoms such as a cough with phlegm, fever, chills, and difficulty breathing.
A variety of organisms, including bacteria, viruses, and fungi, can cause pneumonia. Pneumonia can range in seriousness from mild to life-threatening. It is most serious for infants and young children, people older than 65, and people with underlying health problems or weakened immune systems.
What Are the Symptoms of Pneumonia?
The signs and symptoms of pneumonia vary from mild to severe, depending on factors such as the type of germ causing the infection, your age, and your overall health.
Common symptoms include chest pain when you breathe or cough, confusion or changes in mental awareness (in adults 65 and older), cough that may produce phlegm, fatigue, fever, sweating and shaking chills, lower-than-normal body temperature (in adults older than 65 and people with weak immune systems), nausea, vomiting, or diarrhea, and shortness of breath.
What Causes Pneumonia?
Many germs can cause pneumonia, and they are typically categorized by the setting in which the infection was acquired.
| Type | Description | |---|---| | Community-acquired pneumonia | The most common type, contracted outside of hospitals or other health care facilities. It can be caused by bacteria, bacteria-like organisms, fungi, and viruses. | | Hospital-acquired pneumonia | Contracted during a hospital stay for another illness. This type can be serious because the bacteria causing it may be more resistant to antibiotics. | | Health care-acquired pneumonia | A bacterial infection that occurs in people who live in long-term care facilities or receive care in outpatient clinics. | | Aspiration pneumonia | Occurs when food, drink, vomit, or saliva is inhaled into the lungs. |
Who Is at Risk for Pneumonia?
Pneumonia can affect anyone, but certain groups are at higher risk, including children age 2 or younger, adults age 65 or older, people who have been hospitalized, people with chronic conditions like asthma or heart disease, people who smoke, and people with weakened immune systems.
What Are the Complications of Pneumonia?
Even with treatment, some people with pneumonia, especially those in high-risk groups, may experience complications such as bacteria in the bloodstream (bacteremia), difficulty breathing, fluid accumulation around the lungs (pleural effusion), and lung abscess.
When Should You See a Doctor?
See a doctor if you have difficulty breathing, chest pain, a persistent fever of 102°F (39°C) or higher, or a persistent cough, especially if you're coughing up pus.
It's especially important for the following groups to see a doctor: adults older than 65, children younger than 2 with signs and symptoms, people with an underlying health condition or weakened immune system, and people receiving chemotherapy or taking medication that suppresses the immune system.
How Is Pneumonia Diagnosed?
Your healthcare provider will start with a physical exam, listening to your lungs for abnormal bubbling or crackling sounds that suggest pneumonia.
If pneumonia is suspected, tests may include a blood test to confirm infection and identify the causing organism, a chest X-ray to identify inflammation location and extent, pulse oximetry to measure blood oxygen levels, a sputum test to identify the infection's cause, a CT scan for more detailed lung images, and a pleural fluid culture if fluid is present in the pleural space.
How Is Pneumonia Treated?
Treatment for pneumonia aims to cure the infection and prevent complications.
Antibiotics are used to treat bacterial pneumonia; it may take time to identify the specific bacteria and select the best antibiotic. Cough medicine may be recommended to calm your cough so you can rest, though coughing helps clear fluid from your lungs. Fever reducers/pain relievers, such as acetaminophen or ibuprofen, may be used to manage fever and discomfort as needed.
When Is Hospitalization Needed?
You may need to be hospitalized if you have symptoms including confusion, nausea and vomiting that prevent you from keeping oral antibiotics down, worsened breathing that requires assistance, or a need for a ventilator to help you breathe. Hospitalization may also be needed if your existing health condition worsens due to pneumonia.
Lifestyle and Home Remedies
To help speed recovery and decrease your risk of complications, get plenty of rest, drink plenty of fluids to help loosen secretions and bring up phlegm, and take your full course of any prescribed medication.
How Can Pneumonia Be Prevented?
To help prevent pneumonia, get vaccinated, as vaccines are available to prevent some types of pneumonia and the flu. Practice good hygiene by washing your hands regularly. Avoid smoking, since smoking damages your lungs' natural defenses against respiratory infections. Keep your immune system strong with adequate sleep, a healthy diet, and regular exercise.
Conclusion
Pneumonia is a serious lung infection that requires prompt medical attention, especially for those in high-risk groups. With appropriate treatment, most people recover within one to three weeks, though it may take longer to feel completely back to normal.
If you experience symptoms of pneumonia, particularly if you're in a high-risk group, seek medical care promptly to begin appropriate treatment and reduce the risk of complications.
Frequently Asked Questions
What is pneumonia?
Pneumonia is an infection that inflames the air sacs in one or both lungs, which may fill with fluid or pus, causing cough, fever, and difficulty breathing.
What causes pneumonia?
Pneumonia can be caused by bacteria, viruses, or fungi, and is categorized by where it was acquired: community-acquired, hospital-acquired, health care-acquired, or aspiration pneumonia.
What are the symptoms of pneumonia?
Common symptoms include cough with phlegm, fever, chills, chest pain when breathing, fatigue, and shortness of breath.
How is pneumonia treated?
Treatment depends on the cause; bacterial pneumonia is treated with antibiotics, while supportive care includes rest, fluids, and fever reducers.
Is pneumonia contagious?
Many types of pneumonia, particularly those caused by viruses or bacteria, can be contagious through respiratory droplets.
How long does it take to recover from pneumonia?
Most people improve within one to three weeks with treatment, though fatigue can last longer, especially in older adults.
Can pneumonia be prevented with vaccines?
Yes, vaccines are available that help prevent certain types of pneumonia and the flu, which can lead to pneumonia.
When does pneumonia require hospitalization?
Hospitalization may be needed for severe breathing difficulty, confusion, inability to keep medication down, or worsening of an existing health condition.
Further Reading
Editorial note: This article is for educational purposes only and does not replace professional medical advice. Always consult a qualified healthcare professional for diagnosis and treatment decisions. Content based on current clinical guidance and published medical sources; reviewed August 2026.
Health information, not medical advice. This article is for general education and is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider about your own health, and seek emergency care for urgent symptoms.
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