Lung Infections
Infections affecting the airways and lung tissue
Quick Facts
- Type: Respiratory infection
- Common causes: Viruses, bacteria, fungi
- Main symptoms: Cough, fever, breathlessness
- Seek urgent care: Trouble breathing, blue lips, high fever
Overview
A lung infection is an infection that affects the airways or the deeper tissue of the lungs. The term covers several conditions, including bronchitis (inflammation of the breathing tubes), bronchiolitis in young children, and pneumonia (infection of the tiny air sacs deep in the lungs). These range from mild and self-limiting to severe and life-threatening.
Most lung infections are caused by viruses or bacteria, and many follow a common cold or flu. While healthy people often recover fully, infections can be dangerous for infants, older adults, and people with weakened immune systems or chronic lung disease. Recognizing the warning signs and getting timely care helps prevent serious complications.
Doctors sometimes group lung infections by where they were acquired, such as community-acquired infections that develop in everyday life and hospital-acquired infections that arise during a hospital stay, because the likely germs and treatments can differ. The right approach depends on the type of infection, its severity, and the overall health of the person affected.
Symptoms
Symptoms depend on the type and severity of the infection but commonly include:
- Cough, which may be dry or produce phlegm (mucus) that can be yellow, green, or blood-tinged
- Fever, chills, and sweating
- Shortness of breath or rapid, shallow breathing
- Chest pain or tightness, often worse with coughing or deep breaths
- Wheezing or noisy breathing
- Fatigue, muscle aches, and loss of appetite
Seek emergency care for severe difficulty breathing, bluish lips or face, confusion, a very high fever, or chest pain that does not ease.
Causes
Lung infections are caused by germs that reach the airways or lung tissue, usually through breathing them in or after they spread from the upper airways.
- Viruses: Influenza, respiratory syncytial virus (RSV), rhinoviruses, and coronaviruses are frequent causes, especially of bronchitis and bronchiolitis.
- Bacteria: Streptococcus pneumoniae is the most common bacterial cause of pneumonia; other bacteria can also be responsible.
- Fungi: Less common, mainly affecting people with weakened immune systems.
Inhaling food, liquid, or vomit (aspiration) can also lead to a lung infection.
Risk Factors
- Age under 2 or over 65
- Smoking or exposure to secondhand smoke
- Chronic lung conditions such as asthma, COPD, or bronchiectasis
- Weakened immune system from illness or medication
- Recent cold, flu, or hospital stay
- Difficulty swallowing or reduced consciousness, which raises aspiration risk
Diagnosis
A doctor diagnoses a lung infection from the history, a physical exam, and listening to the chest for abnormal sounds. Tests may include:
- Chest X-ray: To look for pneumonia and rule out other problems.
- Blood tests: To check for infection and how the body is responding.
- Sputum or mucus tests: To identify the responsible germ.
- Pulse oximetry: A clip on the finger that measures blood oxygen levels.
Treatment
Treatment depends on the cause and severity.
- Viral infections: Usually managed with rest, fluids, and fever relief; antiviral medicine is used for certain infections such as influenza.
- Bacterial infections: Treated with antibiotics; it is important to finish the full course.
- Supportive care: Oxygen, breathing treatments, and sometimes hospital care for severe cases.
Antibiotics do not help viral infections, so they are only used when a bacterial cause is suspected. Most mild infections improve within one to two weeks, though a cough can linger longer.
Drinking plenty of fluids, getting rest, and using fever-reducing medicine help the body recover. People at higher risk, such as older adults or those with chronic illness, may be monitored more closely or admitted to hospital so that oxygen levels and breathing can be watched.
Prevention
- Stay up to date with recommended vaccines, including flu and pneumococcal vaccines
- Wash hands often and avoid close contact with sick people
- Do not smoke, and avoid secondhand smoke
- Manage chronic conditions such as asthma and diabetes
- Cover coughs and sneezes to limit spread
When to See a Doctor
Contact a doctor if a cough lasts more than three weeks, if you have a fever with chest pain, or if symptoms are getting worse rather than better. Seek emergency care right away for:
- Severe shortness of breath or struggling to breathe
- Bluish lips, face, or fingertips
- Confusion or unusual drowsiness
- Coughing up blood
- Chest pain that is severe or persistent
Frequently Asked Questions
How do I know if my cough is a lung infection?
A simple cold cough usually improves within a week or two, while a lung infection often comes with fever, colored or bloody phlegm, breathlessness, or chest pain. If your cough lasts more than three weeks or worsens, see a doctor for an exam.
Do lung infections always need antibiotics?
No. Many lung infections are viral and do not respond to antibiotics, which are only used when a bacterial cause is suspected. Taking antibiotics unnecessarily can cause side effects and resistance.
Are lung infections contagious?
Many are. The germs that cause bronchitis and pneumonia can spread through coughs, sneezes, and close contact. Hand washing, covering coughs, and staying home when sick reduce spread.
How long does a lung infection take to clear up?
Mild infections often improve within one to two weeks, though a lingering cough and tiredness can last several weeks. Severe pneumonia may take longer and sometimes needs hospital care.
When is a lung infection an emergency?
Seek emergency care for severe trouble breathing, bluish lips or face, confusion, chest pain that will not ease, or coughing up blood. These can signal a serious or worsening infection.
References
- National Heart, Lung, and Blood Institute (NHLBI). Pneumonia.
- Mayo Clinic. Pneumonia — Symptoms and causes.
- MedlinePlus, U.S. National Library of Medicine. Respiratory tract infections.
- Centers for Disease Control and Prevention (CDC). Pneumonia.