Last updated: Aug 7, 2025Published on: Aug 7, 2025
Table of Contents
Introduction
Did you know that you have an increased risk of developing pneumonia if you are above 65 years of age or under 2 years of age1? Pneumonia is one of the leading causes of death worldwide2.
While pneumonia itself is not contagious, the causative agents (bacteria, virus) generally are. Understanding how pneumonia spreads, what causes it, how to recognise whether your infection is contagious and knowing about the right treatment are essential to protect yourself1.
What Is Pneumonia?
Pneumonia is a serious infection that can affect either one or both of your lungs, causing the air sacs of your lungs or alveoli to be filled with fluid or pus3,4.
Pneumonia is a clinical syndrome with multiple aetiologies and classifications, which include5:
Community-Acquired Pneumonia: Pneumonia acquired outside of hospital settings or in a community setting.
Hospital-Acquired Pneumonia: Pneumonia acquired 48 hours or more of admission in any hospital.
Ventilator-associated Pneumonia: Pneumonia acquired more than 48 hours after endotracheal intubation.
What Causes Pneumonia?
Pneumonia is the inflammation of alveoli in your lungs mostly caused by bacteria, viruses or fungi. These include6,7,8:
Bacterial Pneumonia: Bacteria are a common cause of pneumonia in adults. The most commonly noticed bacterium is Streptococcus pneumoniae while others like Haemophilus influenzae, Bordetella pertussis etc may also be the cause. Atypical bacteria such as Mycoplasma pneumoniae, Chlamydophila pneumoniae, or Legionella are also causes of pneumonia, especially in younger individuals.
Viral Pneumonia: Viruses such as influenza virus, SARS-CoV-2, respiratory syncytial virus (RSV), and rhinovirus can also cause pneumonia.
Fungal Pneumonia: Not as common as bacterial and viral pneumonia, but fungi such as Pneumocystis jirovecii, cryptococcus, histoplasma and blastomyces may also lead to the development pneumonia, especially in individuals with weak immune systems.
Aspiration Pneumonia is one subtype of pneumonia, which occurs when food, liquids, or vomit are inhaled into the lungs, and is not caused by infectious organisms per se9.
Understanding the cause of pneumonia can help to identify whether it is contagious and prevent its spread.
Is Pneumonia Contagious?
This depends upon the underlying cause of pneumonia. Certain types can be contagious based on the causative organism, while others may not spread directly6.
Contagious pneumonia is generally caused by bacteria or viruses, which can be transmitted through respiratory droplets when an infected person coughs, sneezes, or talks6.
Non-contagious pneumonia does not spread from person-to-person. This type of pneumonia occurs due to inhalation of foreign substances (aspiration pneumonia) and is not caused by an infectious agent so cannot spread to others9.
Another type of pneumonia that is less likely to be contagious is that caused by fungal infections, which typically affect people with weakened immune systems. While these are not transmitted between individuals, they can occur in clusters due to shared environmental exposure10,11.
Let’s have a look at the contagious ones in detail.
Which Pneumonia Types are Contagious?
Are you wondering which pneumonia is contagious? Well, as mentioned, not all pneumonias are contagious. Some can spread from person to person, while others do not.
Bacterial pneumonia: Bacteria such as Streptococcus pneumoniae can cause infections that can spread through cough, sneezes, or close contact.
Atypical pneumonia: Some bacteria may cause pneumonia with different symptoms which are usually milder that those in typical pneumonia (referred to as walking pneumonia or atypical pneumonia). This is mostly caused by Mycoplasma pneumoniae, Chlamydia pneumoniae, or Legionella pneumophila and generally affects younger populations. This is contagious and spreads through inhalation of infected respiratory droplets or aerosolised contaminated water.
Viral pneumonia: Viruses such as influenza virus, RSV, or SARS-CoV-2 are also highly contagious and spread similarly via airborne droplets or contact with contaminated surfaces.
Fungal pneumonia: These are acquired from environmental exposure, and person-to-person transmission is exceedingly rare or non-existent, except sometimes in transplant settings (e.g., organ donation from infected donor)12.
How Does Pneumonia Spread?
Pneumonia can spread in several ways, which includes9,10:
Airborne Droplets: This occurs when an individual affected with pneumonia coughs, sneezes or talks. This causes the release of respiratory droplets (infectious as they may contain bacteria or viruses). When you inhale these droplets, you may develop pneumonia.
Contact with Contaminated Surfaces: When an individual touches a surface that is contaminated with bacteria and viruses, and then touches their nose or mouth, they may develop pneumonia.
Aerosols or water droplets: Some organisms which cause pneumonia (such as Histoplasma, Blastomyces, Legionella) are present in the aerosolised soil particles or contaminated water droplets. Hence, when an individual is exposed to these factors, they may inhale an infectious organism and develop pneumonia.
Aspiration: This is not actually a mode for person-to-person transmission, rather a mechanism of entry of oropharyngeal or gastric contents into the lungs. It is a non-infectious event, though it can lead to secondary infection.
Despite these, developing pneumonia depends on host factors, virulence, and exposure dose. Not everyone exposed develops pneumonia. Certain factors may increase risk of pneumonia such as a weakened immune system (this includes HIV, or any chronic diseases like asthma, diabetes, etc). It’s important to be especially vigilant of pneumonia symptoms if you have any preexisting conditions8.
How Long is Pneumonia Contagious?
The contagious period can vary based on the type of pneumonia you are suffering from. The table below lists when pneumonia is contagious6,9:
Type of Pneumonia
Contagious Period
Bacterial Pneumonia
Contagious for approximately 48 hours after starting antibiotics and until fever reduces
Walking Pneumonia
Contagious for several weeks (2-4 weeks before your first symptoms appear and until symptoms resolve)
Viral Pneumonia
Several days to over a week (until fever reduces and symptoms subside)
Fungal Pneumonia
Generally, not contagious
Aspiration Pneumonia
Not contagious
Is Pneumonia Contagious After Antibiotics?
An individual infected with bacterial pneumonia is said to be contagious for approximately 48 hours after starting effective antibiotics, while viral pneumonia may remain contagious longer (several weeks). You are likely to be contagious until your symptoms subside and fever resolves. It is always best to consult your doctor and follow instructions to reduce the spread of infection6.
Symptoms of Pneumonia
The signs and symptoms of pneumonia may include4,13,14:
Fever and chills
Headache
Chest pain (pleuritic pain, which is a sharp pain on breathing and coughing)
Muscle pain or myalgia
Productive cough (may be associated with greenish, yellow or even bloody mucus)
If you are facing any of these symptoms, consult your doctor and seek immediate medical care.
How to Tell If a Cough Might Be Pneumonia
A cough can indicate any infection from a common cold, bronchitis, to pneumonia. The below table summarises the key differences in these 3 infections and helps you to understand if your cough might be pneumonia14,16,17.
Common Cold
Bronchitis
Pneumonia
Duration of Cough
Short duration
Short duration
Persistent Cough
Type of Cough
Productive / nonproductive cough
Productive cough (Clear or yellow-green mucous)
Productive cough (greenish, yellowish or blood stained mucous)
Symptoms
Sore throat, runny nose, sneezing, coughing and headache
Chest discomfort, productive cough, tiredness, low-grade fever, shortness of breath
Rest, fluids, and over-the-counter pain or cold or cough medicines
Rest, fluids, and over-the-counter pain or cold or cough medicines
Antibiotic treatment
Diagnosis
After a careful assessment of your symptoms, your doctor will be able to diagnose your condition with the help of18,19:
Chest X-ray: If you present with clinical symptoms, your chest X-ray may show infiltrates, consolidation, or opacities in your lungs which maybe a sign of pneumonia.
Blood Tests: Your doctor may recommend laboratory tests such as:
Complete blood count: To check for any infections, such as leucocytosis with neutrophilia (bacterial) or lymphocytosis (viral).
Arterial blood gases: Used only in severe cases. It can be used to help assess the oxygenation and acid-base balance in cases of hypoxia or when any other respiratory compromise is expected.
Pulse Oximetry: To measure your oxygen level in your blood. Pneumonia fills air spaces in lungs with fluids, impairing gas exchange, which leads to hypoxemia. If you are suffering from pneumonia, it can prevent your lungs from getting enough oxygen into your blood.
Sputum Test: To identify the organism causing your illness.
Blood Culture Test: To identify the causative agent and to check for bacterial infection in your blood which has prognostic implications in severe CAP or suspected sepsis.
Polymerase Chain Reaction (PCR) Test: To identify the DNA of the causative agent
Bronchoscopy: A tube is inserted into your airway and your doctor may collect samples of the tissue and fluid from your lungs to identify the cause of your pneumonia. This method is only done in complicated cases, cases of unresolved pneumonia or immunocompromised patients.
Chest Computed Tomography (CT) Scan: This tool can help to identify the extent to which your lungs are affected by pneumonia and can also identify abscesses and other lung disorders.
Based on these tests, your doctor will be able to accurately diagnose your condition and will suggest the appropriate treatment for your condition18.
Treatment for Pneumonia
Depending on the type of pneumonia you have, your doctor may suggest the following treatments20,21:
Bacterial pneumonia: Antibiotics may be prescribed. You should start to notice a reduction in your symptoms in 48-72 hours. However, complete recovery can take a much longer time in elderly patients (several weeks). Take your medications as prescribed by your doctor and do not discontinue your medication.
Viral pneumonia: While in most cases, viral pneumonias clear up by itself, Influenza, RSV and SARS-CoV-2 can cause severe disease, especially in children, elderly individuals and individuals who are immunocompromised. Oseltamivir may be prescribed for managing influenza, ribavirin may be prescribed for RSV, parainfluenza virus, adenovirus, and measles virus22.
Fungal pneumonia: Treatment prescribed is dependent on the causative organism. For example, if your infection is caused by Pneumocystis jirovecii, your doctor may prescribe a combination of trimethoprim-sulfamethoxazole, or if your infection is caused by Histoplasma, your doctor may prescribe itraconazole or amphotericin B for the management of your condition22.
Apart from these medications, it is important to get plenty of rest, drink plenty of fluids, and you may take over-the-counter medications for pain, cough, cold and fever.
In cases of severe pneumonia, you may have to be a hospitalised to receive medications (antibiotics and fluids) through an intravenous (IV) line. Your doctor may also recommend oxygen therapy to increase the amount of oxygen in your blood. If you are suffering from a serious infection, you may need ventilator support20,21.
Prevention Tips
Taking a few proactive steps and getting vaccinated, can reduce your chances of developing pneumonia. This includes23:
Apart from getting vaccinated, certain simple tips that you can follow to protect yourself against pneumonia include23,25:
Avoid close contact with infected and sick individuals.
If you are sick, stay at home to prevent the spread of infection.
When in a public place, cover your nose and mouth with a tissue while sneezing and coughing or cough or sneeze into your elbow followed by good hand hygiene.
Quit smoking and avoid alcohol consumption.
Make sure you wash your hands regularly with warm water and soap for at least 20 seconds.
It is important to clean and disinfect frequently contacted surfaces to reduce the risk of infection.
Consult your doctor for any medical issues such as heart disease, diabetes and take medications as directed. These conditions can lead to secondary pneumonia and managing them is essential for pneumonia prevention.
When to See a Doctor
You should consult a doctor if you experience symptoms of pneumonia. If you face difficulty in breathing, high fever, difficulty breathing, chest pain, and a productive cough, seek immediate medical care26.
Moreover, it is important to get immediate medical care in high-risk individuals (adults over the age of 65, children below the age of 2 and adults with any underlying health condition such as diabetes, heart disease) or weakened immune system (immunocompromised individuals) as the disease can progress quickly in these individuals. Moreover, if you notice symptoms such as bluish lips or nails (cyanosis), confusion, and rapid breathing, it is best to seek prompt medical care26,27.
Conclusion
Talking about the main question – is pneumonia contagious in adults? Well, it may or may not be, depending on its underlying cause. It is important to recognise the type of pneumonia you have and how it may be transmitted. Taking appropriate precautions such as getting timely vaccinations and promoting good hygiene can help prevent its spread. Early diagnosis and treatment are essential for a quick recovery.
Frequently Asked Questions (FAQs)
What are the complications of pneumonia, if left untreated?
The complications of untreated or incompletely treated pneumonia include respiratory failure, accumulation of pus in between the lung and the lining of the chest wall (empyema), lung abscess, sepsis and may also lead to multi organ failure5.
Is pneumonia more dangerous during pregnancy?
Yes, pregnant individuals are at higher risk of complications of pneumonia such as low weight at birth and increased risk of preterm birth due to weakened immunity28.
Can pets transmit pneumonia to humans?
Yes, this can occur, though rarely. Certain infections such as Q fever (caused by Coxiella burnetii) and Psittacosis (caused by Chlamydophila psittaci) may occur in individuals working closely with animals or livestock29,30.
What is the difference between bronchitis and pneumonia?
Bronchitis affects your bronchial tubes (airways), while pneumonia affects the air sacs (alveoli) in the lungs. The symptoms of pneumonia tend to be more severe and may involve high-grade fever, chest pain, and shortness of breath14,17.
Troeger C, Blacker B, Khalil IA, Rao PC, Cao J, Zimsen SRM, et al. Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory infections in 195 countries, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. The Lancet Infectious Diseases [Internet]. 2018 Nov;18(11):1191–210. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6202443/
Smith DJ, Williams SL, Benedict KM, Jackson BR, Toda M, Adame G, et al. Surveillance for Coccidioidomycosis, Histoplasmosis, and Blastomycosis — United States, 2019. MMWR Surveillance Summaries [Internet]. 2022 Aug 19;71(7):1–14. Available from: https://www.cdc.gov/mmwr/volumes/71/ss/ss7107a1.htm
José RJ, Periselneris JN, Brown JS. Opportunistic bacterial, viral and fungal infections of the lung. Medicine [Internet]. 2020 Jun 1;48(6):366–72. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7206443/
Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.
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