ConditionLungs & breathing
Lung Infections (Chest Infections)
Lung infections, also called chest infections or lower respiratory tract infections, are infections of the airways or lung tissue caused by viruses, bacteria or, less often, fungi. The main types are acute bronchitis, pneumonia, bronchiolitis in babies, and tuberculosis. They cause cough, mucus, fever, breathlessness and chest discomfort. Bronchitis is usually viral and clears on its own, while pneumonia may need antibiotics and sometimes hospital care. Fast breathing, confusion or blue lips need emergency help.
Also called: Chest infections, lower respiratory tract infections, respiratory infections, LRTI
At a glance
- What they are
- Infections of the bronchi (airways), bronchioles or alveoli (air sacs).
- Main types
- Acute bronchitis, pneumonia, bronchiolitis, tuberculosis, whooping cough and fungal infections.
- Causes
- Mostly viruses (flu, RSV, COVID-19, rhinovirus); bacteria such as pneumococcus cause many pneumonias.
- Key symptoms
- Cough, mucus, fever, breathlessness, chest pain and tiredness.
- Treatment
- Rest and fluids for viral infections; antibiotics for bacterial pneumonia; antivirals for flu or COVID-19 in some.
When to get help
Call 911 or go to the ER
- Severe breathlessness, struggling to breathe, or unable to speak in full sentences
- Blue or gray lips, face or fingertips
- Confusion, extreme drowsiness or collapse
- Chest pain with breathlessness, or coughing up large amounts of blood
- A baby with pauses in breathing, grunting, ribs pulling in, or unable to feed
See a doctor within a day or two
- Fever of 39 °C (102.2 °F) or higher, or any fever with breathlessness
- Breathing faster than usual at rest, or sharp chest pain when breathing in
- Symptoms that improve and then get worse
- A chest infection in someone over 65, pregnant, or with heart, lung or kidney disease, diabetes or a weak immune system
- A cough lasting more than 3 weeks with weight loss or night sweats (possible tuberculosis)
Book a routine appointment
- A cough that has not improved after 3 weeks
- Frequent chest infections
- Cough with blood-streaked mucus once or twice
Usually safe to manage at home
- A cough with clear, yellow or green mucus and mild fever in an otherwise healthy adult who can breathe comfortably and is improving
Types of lung infection
| Infection | Where | Typical cause | Typical features |
|---|---|---|---|
| Acute bronchitis | Large airways | Viruses (over 90%) | Cough for up to 3 weeks, mucus, mild fever; lungs clear on exam |
| Pneumonia | Air sacs | Bacteria (pneumococcus), viruses, atypical bacteria (mycoplasma) | Fever, breathlessness, chest pain, crackles; X-ray changes |
| Bronchiolitis | Small airways in babies | RSV mainly | Under 2 years; cough, wheeze, fast breathing, feeding problems |
| Tuberculosis | Lungs and elsewhere | Mycobacterium tuberculosis | Cough for weeks, weight loss, night sweats, fever |
| Whooping cough | Airways | Bordetella pertussis | Coughing fits with a "whoop" and vomiting; dangerous in babies |
| Infective exacerbation of COPD or bronchiectasis | Damaged airways | Viruses and bacteria | More breathlessness and sputum in chronic lung disease |
| Fungal infections | Lungs | Aspergillus, histoplasma, pneumocystis | Mostly weak immunity or specific exposures |
| Lung abscess and empyema | Lung tissue or around the lung | Bacteria, often after aspiration | Persistent fever, foul sputum, chest pain |
Upper respiratory infections, such as colds and sore throats, affect the nose and throat and are not lung infections, though they can spread down.
Symptoms
- cough, dry or with mucus (phlegm) that may be clear, yellow, green or rusty
- fever, chills and sweats
- shortness of breath
- chest pain or tightness, often sharp when breathing in (pleuritic pain) with pneumonia
- wheezing
- tiredness, aches and loss of appetite
- in older adults: confusion or falls may be the main sign, sometimes without fever
Bronchitis vs pneumonia
| Bronchitis | Pneumonia | |
|---|---|---|
| Fever | None or low | Often high |
| Breathlessness | Mild or none | Common |
| Breathing rate | Normal | Often fast |
| Chest exam | Usually clear | Crackles, reduced breath sounds |
| Chest X-ray | Normal | Patchy shadowing |
| Antibiotics | Usually not helpful | Usually needed if bacterial |
Who is at higher risk
- babies and adults over 65
- smokers and vapers
- people with asthma, COPD, bronchiectasis or heart failure
- diabetes, kidney or liver disease
- weakened immunity: HIV, chemotherapy, transplant medicines, steroids
- difficulty swallowing, stroke or dementia (risk of aspiration)
- living in care homes or crowded settings
Diagnosis
- Examination: temperature, breathing rate, oxygen levels and listening to the chest
- Chest X-ray: to confirm pneumonia
- Tests: viral swabs for flu, COVID-19 and RSV; sputum and blood cultures in more severe illness; blood tests for inflammation
- TB tests: sputum samples, chest X-ray and interferon-gamma release assays when TB is suspected
- Severity scores such as CURB-65 help decide who needs hospital care
Treatment
- Viral bronchitis and mild viral infections: rest, fluids, honey for cough (not under 12 months), and acetaminophen (paracetamol) or ibuprofen for fever, following the label dose. Antibiotics do not help.
- Bacterial pneumonia: antibiotics, usually for 5 days or more depending on severity, by mouth or IV.
- Flu and COVID-19: antivirals for high-risk people or severe illness, ideally started early.
- Bronchiolitis: supportive care: fluids, suctioning the nose, oxygen if needed.
- Tuberculosis: a combination of antibiotics for at least 4 to 6 months.
- Hospital care: oxygen, IV fluids, IV antibiotics and breathing support for severe illness.
Stop smoking, and do not vape, to help recovery.
Recovery
A bronchitis cough often lasts 2 to 3 weeks. After pneumonia, fever usually settles within days of treatment, but tiredness and cough can last 4 to 6 weeks or longer, especially in older adults.
Prevention
- Vaccines: flu (yearly), COVID-19, pneumococcal (for adults 50 and over and younger people at risk, under current US recommendations), RSV (older adults, pregnancy and infant protection), and whooping cough (Tdap, including in pregnancy)
- Stop smoking and avoid secondhand smoke
- Hand washing and covering coughs
- Manage chronic conditions such as asthma, COPD and diabetes
Frequently asked questions
What are the symptoms of a lung infection?
Common symptoms are a cough with or without mucus, fever, chills, shortness of breath, chest pain when breathing, wheezing and tiredness. Older adults may become confused without much fever. Struggling to breathe or blue lips need emergency care.
Is a lung infection contagious?
Many are. Viral and bacterial lung infections spread through droplets from coughs and sneezes and through contaminated hands. Tuberculosis spreads through the air over longer contact. Washing hands, covering coughs and staying home when ill reduce spread.
How do I know if I have bronchitis or pneumonia?
Bronchitis usually causes a cough with little or no fever and no significant breathlessness. Pneumonia more often causes high fever, fast breathing, breathlessness and chest pain. A doctor can examine your chest and order an X-ray to tell them apart.
Do lung infections need antibiotics?
Not always. Most bronchitis and many chest infections are caused by viruses, which antibiotics do not treat. Bacterial pneumonia, whooping cough and tuberculosis need antibiotics. A doctor decides based on symptoms, examination and sometimes tests.
How long does a lung infection last?
Acute bronchitis usually improves within 1 to 3 weeks, though the cough may linger. Recovery from pneumonia often takes 2 to 6 weeks, longer in older adults or severe cases. Tuberculosis needs months of treatment.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Pneumonia; Chest cold (acute bronchitis)
- American Thoracic Society/IDSA: Diagnosis and treatment of adults with community-acquired pneumonia guideline
- NICE: Pneumonia (community-acquired) - antimicrobial prescribing (NG138)
- American Lung Association: Lung infections
- World Health Organization: Pneumonia in children