Causes of Lung Infections Explained
Uncover the common causes of lung infections, from viruses and bacteria to fungi and environmental factors. Understand how these pathogens attack your respiratory system, leading to conditions like bronchitis and pneumonia, and learn about prevention.
Written by Dr. Md Yusuf Shareef
Reviewed by Dr. Rohinipriyanka Pondugula MBBS
Last updated on 19th Aug, 2025
Lung infections can be uncomfortable and sometimes even dangerous if not addressed properly. Understanding what causes them can help you take steps to prevent or manage them effectively. In this article, we’ll break down the common causes of lung infections, their symptoms, and how you can protect yourself.
What Is a Lung Infection?
A lung infection occurs when harmful germs—such as bacteria, viruses, or fungi—invade your lungs, leading to inflammation and breathing difficulties. Common lung infections include:
- Pneumonia (bacterial, viral, or fungal)
- Bronchitis (often viral)
- Tuberculosis (TB) (bacterial)
- Fluorolated lung infections
These infections can range from mild to severe, depending on the cause and your overall health.
Common Causes of Lung Infections
Common causes of lung infections are:
1. Bacterial Infections
Bacteria are a leading cause of lung infections, especially pneumonia. Common bacteria responsible include:
- Streptococcus pneumoniae (most common cause of bacterial pneumonia)
- Mycobacterium tuberculosis (causes TB)
- Haemophilus influenzae (can lead to bronchitis and pneumonia)
Bacterial infections often require antibiotics for treatment.
2. Viral Infections
Viruses are another major cause, especially in cases of:
- Influenza (flu virus)
- Respiratory Syncytial Virus (RSV) (common in children)
- COVID19 (SARSCoV2)
- Common cold viruses (rhinovirus, adenovirus)
Viral lung infections usually improve on their own, but severe cases may need medical attention.
Consult Top Specialists
3. Fungal Infections
Fungal lung infections are less common but can be serious, especially in people with weakened immune systems. Examples include:
- Histoplasmosis (from inhaling spores in soil or bird droppings)
- Aspergillosis (from mold exposure)
- Pneumocystis pneumonia (PCP) (common in HIV/AIDS patients)
4. Environmental Factors
Certain conditions can increase the risk of lung infections:
- Air pollution (smoke, dust, chemicals)
- Smoking or secondhand smoke (damages lung defenses)
- Mold and damp environments (can trigger fungal infections)
5. Weakened Immune System
- People with chronic illnesses (like diabetes, HIV, or cancer) or those on immunosuppressive medications are more prone to lung infections.
6. Aspiration (Inhaling Foreign Substances)
- Accidentally inhaling food, liquids, or stomach acid into the lungs can cause infection (aspiration pneumonia). This is more common in older adults or people with swallowing difficulties.
Symptoms of a Lung Infection
Watch out for these signs:
- Persistent cough (with or without mucus)
- Shortness of breath
- Chest pain (especially when breathing or coughing)
- Fever, chills, and fatigue
- Wheezing or noisy breathing
- Bluish lips or nails (indicates low oxygen—seek help immediately)
If symptoms worsen or last more than a few days, consult a doctor.
How to Prevent Lung Infections?
Ways to prevent lung infections are:
1. Practice Good Hygiene
- Wash hands frequently with soap and water.
- Use hand sanitizer when soap isn’t available.
- Avoid touching your face, especially your nose and mouth.
2. Get Vaccinated
Vaccines can protect against:
- Flu (annual flu shot)
- Pneumonia (pneumococcal vaccine)
- COVID19
- Whooping cough (pertussis)
3. Avoid Smoking & Pollutants
- Quit smoking and avoid secondhand smoke.
- Wear a mask in polluted or dusty areas.
- Keep indoor air clean with air purifiers if needed.
4. Strengthen Your Immune System
- Eat a balanced diet (rich in fruits, vegetables, and proteins).
- Stay hydrated.
- Exercise regularly to improve lung function.
- Get enough sleep (7-9 hours per night).
5. Manage Chronic Conditions
- If you have asthma, COPD, or diabetes, follow your treatment plan to reduce infection risks.
When to See a Doctor?
Seek medical help if you experience:
- High fever (above 101°F or 38.3°C)
- Difficulty breathing
- Coughing up blood
- Confusion or extreme fatigue
- Symptoms lasting more than a week
Early treatment can prevent complications.
Need Help? Consult a Specialist
If you suspect a lung infection or need preventive care, Apollo 24|7 offers expert consultations and diagnostic tests. You can easily book an appointment online and get the right treatment from trusted doctors.
Final Thoughts
Lung infections can be caused by bacteria, viruses, fungi, or environmental factors. By understanding the causes and taking preventive steps, you can protect your lungs and stay healthy. If you experience severe symptoms, don’t hesitate to seek medical advice.
Stay informed, stay safe, and breathe easy!
Book a consultation today with Apollo 24|7 for expert care.
Consult Top Specialists
Consult Top Specialists
Dr. Rajib Ghose
General Practitioner
25 Years • MBBS
East Midnapore
VIVEKANANDA SEBA SADAN, East Midnapore
Dr. Ramya Hari
General Practitioner
18 Years • Medical Head & Family Physician, DG Shipping Approved Doctor, Panel Physician - UK Visa Medicals
Chennai
Apollo Medical Centre Kotturpuram, Chennai
Dr. Indrajit Das
General Physician/ Internal Medicine Specialist
4 Years • "MD (Internal medicine) : Gauhati Medical College and Hospital, Guwahati (2018-2021) MD (Pathology) : Gauhati Medical College and Hospital, Guwahati (2012-2015) MBBS (Bachelor of Medicine, Bachelor of Surgery) : Silchar Medical College, Assam (2003-2008) "
Guwahati
Apollo Excelcare Hospital, Guwahati
Dr. Mohammed Sharouk Khader
General Physician/ Internal Medicine Specialist
11 Years • MBBS, Bach. of Med. & Surg., Dip. of American Board of Family Med.
Chennai
Apollo Hospitals Greams Road, Chennai
(125+ Patients)
Dr. Ajay K Sinha
General Physician/ Internal Medicine Specialist
30 Years • MD, Internal Medicine
Delhi
Apollo Hospitals Indraprastha, Delhi
(200+ Patients)
Consult Top Specialists
Dr. Rajib Ghose
General Practitioner
25 Years • MBBS
East Midnapore
VIVEKANANDA SEBA SADAN, East Midnapore
Dr. Ramya Hari
General Practitioner
18 Years • Medical Head & Family Physician, DG Shipping Approved Doctor, Panel Physician - UK Visa Medicals
Chennai
Apollo Medical Centre Kotturpuram, Chennai
Dr. Indrajit Das
General Physician/ Internal Medicine Specialist
4 Years • "MD (Internal medicine) : Gauhati Medical College and Hospital, Guwahati (2018-2021) MD (Pathology) : Gauhati Medical College and Hospital, Guwahati (2012-2015) MBBS (Bachelor of Medicine, Bachelor of Surgery) : Silchar Medical College, Assam (2003-2008) "
Guwahati
Apollo Excelcare Hospital, Guwahati
Dr. Mohammed Sharouk Khader
General Physician/ Internal Medicine Specialist
11 Years • MBBS, Bach. of Med. & Surg., Dip. of American Board of Family Med.
Chennai
Apollo Hospitals Greams Road, Chennai
(125+ Patients)
Dr. Ajay K Sinha
General Physician/ Internal Medicine Specialist
30 Years • MD, Internal Medicine
Delhi
Apollo Hospitals Indraprastha, Delhi
(200+ Patients)
