Pneumonia: Symptoms, Causes, Treatment & More

Medically reviewed by Mary Lucas, RN

Written by Our Editorial Team

Last updated 11/25/2020

Pneumonia is an infection that can occur in one or both of the lungs, causing the air sacs of the lungs to become inflamed and filled with fluid or pus.

Several different types of germs, including bacteria, fungi and viruses, can cause pneumonia to develop. It’s also possible for pneumonia to develop if you inhale a substance that irritates the lungs, such as a chemical or a liquid.

Pneumonia can affect people of all ages. However, people older than 65 or younger than two, as well as those with pre-existing health conditions, are typically the most at risk of developing pneumonia.

Below, we’ve listed the symptoms and complications of pneumonia. We’ve also explained how pneumonia can develop, how it’s typically diagnosed by a healthcare professional and the treatment options and prevention methods that are currently available.

Symptoms of Pneumonia

Pneumonia causes inflammation of the air sacs of your lungs, or alveoli. It can cause a range of symptoms, including:

  • Fever, sometimes with sweating, chills and shaking

  • Cough, including coughing with green, yellow or bloody mucus

  • Fast, shallow breathing

  • Shortness of breath

  • Severe, sharp chest pain, especially when coughing or breathing deeply

  • Nausea and vomiting

  • Fatigue and reduced energy

  • Loss of appetite

  • Confusion (usually in older people)

Pneumonia can be caused by bacterial, viral or fungal infections. Pneumonia that’s caused by bacteria, known as bacterial pneumonia, generally causes more serious symptoms than other forms of pneumonia. 

If you have bacterial pneumonia, you may experience the following symptoms: 

  • High fever, including a dangerous fever of 105°F or higher

  • Significant, profuse sweating

  • Very high pulse rate and rapid breathing

  • Bluish color in the lips and nailbeds due to lack of oxygen

  • Confused and/or delirious mental state

Pneumonia that’s caused by a virus, known as viral pneumonia, generally starts with symptoms similar to those of influenza (flu). If you have viral pneumonia, you may experience the following symptoms:

  • Dry cough

  • Shortness of breath

  • Fever

  • Muscle pain

  • Headache

  • Weakness

  • Blueness of the lips

In addition to pneumonia from bacteria, fungi or viruses, pneumonia can also result from accidental inhalation of food, vomit or saliva into the lungs. This is known as “aspiration pneumonia.” 

Those most at risk for this type of pneumonia include the elderly, people who have impaired alertness due to intoxication or the influence of medications, people in a coma, and those who have impaired ability to swallow due to, for example, having had a stroke. 

The symptoms of pneumonia can vary in severity. If you have pneumonia, you may only notice mild symptoms, or not notice any symptoms at all.

Who is Most at Risk of Severe Symptoms and Complications?

Some people may experience severe symptoms from pneumonia. Severe symptoms are more common in children under the age of five, adults above the age of 65 and people with serious, pre-existing medical conditions such as the following:

  • Heart failure

  • Diabetes

  • Chronic obstructive pulmonary disease (COPD) and other chronic lung conditions

  • Weakened immune system due to HIV/AIDS

In addition to people with chronic health conditions, people undergoing chemotherapy to treat cancer and people who have undergone organ or blood and marrow stem cell transplant procedures may have a higher risk of experiencing severe symptoms from pneumonia.

Potential Complications Associated With Pneumonia

Not all cases of pneumonia lead to complications. However, in people with a high risk of severe complications, and/or if the illness isn’t properly treated, pneumonia may potentially lead one or several of the following complications:

  • Lung abscesses. These occur when cavities containing pus form in the tissue of the lungs. They’re usually treated with antibiotics, surgery or drainage of the abscess using a needle.

  • Pleural effusions, empyema and pleurisy. These potential complications can develop when severe pneumonia is left untreated. Effusions involve the build-up of fluid or pus (empyema) in the layers of tissue that surround the lung and separate it from the chest wall. Inflammation of these layers is known as pleurisy.

    When severe, these complications cause severe pain and, in some cases, can even be fatal.

  • Bacteremia and septic shock. When pneumonia is caused by a bacterial infection, the bacteria from the site of the infection can spread into the blood and cause the potentially fatal complication septic shock.

  • Kidney injury and renal failure. Pneumonia can cause damage to the kidneys. Studies have found that patients who are hospitalized with pneumonia are at high risk of developing renal failure.

  • Respiratory failure. Severe pneumonia may potentially cause respiratory failure — a condition in which the respiratory system fails to supply the body with enough oxygen while eliminating carbon dioxide, leading to signs and symptoms such as loss of consciousness, abnormal heart rhythms and can be fatal if it occurs acutely.

When Should You Talk to a Healthcare Provider?

If you belong to one of the high-risk groups listed above and believe that you have pneumonia, it’s important to seek medical help to avoid complications. Talk to a healthcare provider as soon as possible, or seek immediate help if you believe you’re experiencing a medical emergency. 

Pneumonia can quickly become a life-threatening condition if not treated. Contact your healthcare provider as soon as possible, even if you don’t feel that your current symptoms are serious. 

You should also talk to a healthcare provider right away if you experience any of the following symptoms:

  • Persistent fever of 102°F (38.9°C) or higher

  • Persistent cough, especially with pus

  • Difficulty breathing

  • Chest pain

The symptoms of pneumonia can worsen quickly. If you think that you have pneumonia, it’s best to talk to a healthcare provider if you feel at all worried about your health, even if you aren’t experiencing any severe symptoms.

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What Causes Pneumonia?

Pneumonia is caused by numerous different germs, including common bacteria and viruses. In some cases, pneumonia can develop due to inhalation of fungi or chemicals. We’ve explained how each of these causes can lead to pneumonia below. 


Most pneumonia is caused by bacterial infection. In the US, Streptococcus pneumoniae is the bacteria most commonly linked to cases of pneumonia. 

Other types of infectious bacteria can also cause pneumonia. When pneumonia is caused by a bacteria other than Streptococcus pneumoniae, it’s typically called atypical pneumonia. Bacteria that can cause atypical pneumonia include:

  • Mycoplasma pneumoniae. This bacteria usually causes a mild form of pneumonia (commonly referred to as “walking pneumonia”) that’s treatable using antibiotics. One of the risk factors of getting this type of pneumonia is living and working in crowded conditions such as shelters, dormitories, etc. Pneumonia caused by Mycoplasma pneumoniae is common in people under the age of 40.

    Although pneumonia caused by Mycoplasma pneumoniae is usually mild, it can cause serious complications in some cases.

  • Legionella pneumophila. Pneumonia caused by Legionella pneumophila is often called Legionnaires disease. This type of pneumonia can result in large-scale outbreaks and is often linked to exposure to fountains, whirlpool spas and cooling towers.

  • Chlamydia pneumoniae. Pneumonia caused by Chlamydia pneumoniae is common in people aged 65 and older. It’s usually mild and can develop at any time of year.

Bacterial pneumonia, including atypical pneumonia, can develop after you’ve had a viral illness such as a cold or the flu, or on its own. In some cases, it may only affect one lobe of a lung. This is called lobar pneumonia.


Pneumonia is often caused by a viral respiratory infection. When pneumonia is caused by a viral infection, it’s referred to as viral pneumonia.

The most common cause of viral pneumonia in adults is influenza (flu). Other viruses that can cause viral pneumonia include the common cold (rhinovirus), human parainfluenza virus (HPIV), human metapneumovirus (HMPV) and, in young children, respiratory syncytial virus (RSV).

Viral pneumonia is usually mild and gets better on its own over the course of several weeks with no need for treatment. However, some people with viral pneumonia can still develop severe and potentially dangerous complications, making it important to pay close attention to symptoms.


Pneumonia can also develop due to a fungal infection. One type of fungal pneumonia is pneumocystis pneumonia, which is caused by the fungus Pneumocystis jirovecii.

Pneumocystis jirovecii typically occurs in people with weakened immune systems, either due to health conditions such as HIV/AIDS or through use of immunosuppressive medications such as those used after organ transplantation, blood or bone marrow transplantation, or certain cancer treatments.

Certain regional fungi can also cause fungal pneumonia. For example, the Histoplasma fungus, which is found in soil in the central, southeastern, and mid-Atlantic regions, can cause a type of infection called histoplasmosis, which may lead to pneumonia.

Other fungal infections that can potentially lead to pneumonia include coccidioidomycosis and cryptococcus.


Some chemicals can irritate and damage the lung tissue and cause a condition called chemical pneumonitis. Although this isn’t infectious, it’s often referred to as chemical pneumonitis due to its symptoms. 

Chemical pneumonitis can be caused by many chemicals, including fumes from pesticides and fertilizers, smoke, and poisonous gases such as chlorine gas.

Other Classifications of Pneumonia

Most cases of pneumonia are referred to as community-acquired pneumonia. These cases are typically linked to bacteria, viruses and fungi found outside of healthcare facilities and hospitals and spread through the community. 

It’s also possible for pneumonia to develop in a hospital or healthcare facility setting. People in a hospital for other illnesses may develop pneumonia from a bacterial infection that they acquired while in care. This form of pneumonia is referred to as hospital-acquired pneumonia.

Hospital-acquired pneumonia can be extremely severe and, in some cases, even fatal. This is because people undergoing treatment in hospital are often already sick, affecting their ability to fight off the bacteria and viruses that can cause pneumonia.

The bacteria found in hospitals may also be more difficult to treat, as it’s often more resistant to antibiotics than the bacteria that cause community-acquired pneumonia.

Pneumonia can also develop in a healthcare facility setting, such as an outpatient clinic or care facility. This type of pneumonia is referred to as Health care-associated pneumonia (HCAP) and is most common in high-risk people, such as people with a compromised immune system.

Who is Most at Risk?

Strep throat is most common in the very young and people aged 65 and up. Children under the age of two years have a higher risk of developing pneumonia as their immune systems are not yet fully developed.

People aged 65 and older have a higher risk of developing pneumonia due to changes to their immune systems that occur as part of the aging process.

Other factors, such as your environment and lifestyle, may increase your risk of developing pneumonia. You may have a higher risk of getting pneumonia if you:

  • Smoke cigarettes or other tobacco products.

  • Drink alcohol frequently in excessive amounts.

  • Don’t eat enough food to be in good health.

  • Work or spend time in an environment with toxic fumes, chemicals or other types of hazardous pollutants.

Certain medical conditions can also increase your risk of developing pneumonia. You may have a higher risk of getting pneumonia if you: 

  • Have a serious health condition, such as heart failure, diabetes or sickle cell disease, or a disease that affects your breathing such as asthma, cystic fibrosis, chronic obstructive pulmonary disease (COPD) or bronchiectasis.

  • Have a suppressed or weakened immune system due to HIV/AIDS, long-term steroid use, chemotherapy, organ transplant, stem cell transplant or other medical condition, procedure or treatment that may affect your immune health.

  • Are currently in an intensive-care unit for another disease or condition, particularly if you are currently using a ventilator to assist with breathing.

  • Have difficulty breathing or swallowing due to a stroke or other medical condition.

  • Have recently had chest surgery or other major surgery.

  • Can’t move easily due to injury, disability or sedation.

  • Have recently had the flu or a cold.

Diagnosis of Pneumonia

The symptoms of pneumonia can be quite similar to those of a common cold or the flu. This means that it can sometimes be difficult to diagnose. Your healthcare provider will typically ask several questions and perform a physical exam to check for the symptoms of pneumonia.

Your healthcare provider may ask about your occupation and your level of potential exposure to people who could transmit bacterial or viral infections. They may also ask about recent travel, illnesses and other relevant topics.

You may be asked if you smoke, as well as how much and how frequently. Your healthcare provider may ask about any existing health conditions that you have.

To check for physical symptoms of pneumonia, your healthcare provider may use a stethoscope to listen to the activity of your lungs. If you have pneumonia, your lungs may produce rales (a rattling-like sound) and ronchi (coarse respiratory sounds similar to snoring) when you breathe.

If your physical exam suggests that you may have pneumonia, your healthcare provider may ask you to take one or several tests to provide more information. Tests used to diagnose pneumonia include:

  • Blood tests. Certain blood tests, such as a complete blood count (CBC), can confirm that you have an infection and help your healthcare provider to identify the specific bacteria or virus that’s causing your symptoms.

  • Blood culture. This type of test checks for foreign bacteria and other microorganisms that could have infected your blood. The results can help your healthcare provider detect if you have an infection that’s spread into your bloodstream.

  • Chest X-ray. This can help your healthcare provider to identify and locate any inflammation in your lungs.

  • Sputum test. This test uses a sputum sample (saliva and mucus from your respiratory tract) to check for bacteria and/or viruses in your lungs and breathing passages.

  • Pulse oximetry test. Pneumonia can affect the performance of your lungs, resulting in reduced oxygen levels. This test measures the oxygen level (oxygen saturation) of your blood, providing more information to your healthcare provider about a possible infection.

If you’re above the age of 65, or have a pre-existing condition or other factor that puts you at a high risk of developing complications, your healthcare provider may request one or several or the following additional tests:

  • CT scan of the chest. This allows your healthcare provider to check for abscesses, pleural effusions and other signs of complications, as well as how much of your lungs are affected by the condition.

  • Pleural fluid culture. This test involves the collection of a fluid sample from your pleural cavity, the fluid-filled space between your lungs and chest cavity. Your healthcare provider may check this sample for pneumonia-causing bacteria.

  • Bronchoscopy. This procedure allows your healthcare provider to look directly into your lungs using a small camera. Your healthcare provider may order a bronchoscopy to collect fluid samples, to take a biopsy from the lungs, or to identify more information about your condition.

Pneumonia Treatment and Prevention

If your healthcare provider diagnoses you with pneumonia, they’ll work together with you to make sure you’re treated effectively. 

Treatment for pneumonia can vary based on the specific type of pneumonia that you have, how severe your symptoms are, as well as your general health and risk of developing any potentially dangerous complications. 

Over-the-Counter Medications

To treat the symptoms of pneumonia, your healthcare provider may recommend using medication to control your fever and level of pain. Medications such as acetaminophen (Tylenol), ibuprofen (Advil® or Motrin IB®) and aspirin may help to make these symptoms easier to live with.

If your child has pneumonia, make sure that you don’t give them aspirin, as it may increase their risk of developing a rare condition called Reye’s syndrome.

If you have a cough, it’s important to talk to your healthcare provider before using cough medicine. Coughing is part of your body’s natural response to an infection. If you have a severe or painful cough and want to treat it, ask your healthcare provider for safe, effective treatments before using any medication.

Antibiotics and Antiviral Medications

If your pneumonia is caused by a bacterial infection, your healthcare provider may prescribe an antibiotic. It’s important to take this medication exactly as prescribed by your healthcare provider in order to completely get rid of the bacteria, even if you no longer have pneumonia symptoms.

Stopping treatment with antibiotics early may increase the risk of your bacterial infection coming back with an increased resistance to medication.

If your pneumonia is caused by a virus, antibiotics won’t be effective. Your healthcare provider may recommend using an antiviral medication. This type of medication slows down the spread of the virus in your body and may help to speed up your recovery.

Home Remedies and Lifestyle Changes

If you have pneumonia, the following home remedies and lifestyle changes may help to make your symptoms easier to deal with:

  • Stop smoking. Smoke irritates your lungs, making the symptoms of pneumonia more severe. If you’re a smoker, it’s best to avoid smoking while you’re sick, or make a real effort to quit for good.

  • Get plenty of rest. Rest plays a major role in helping your body recover from illnesses, including pneumonia. Take it easy while you feel sick and spend plenty of time in bed to give yourself the strength to fully recover.

  • Stay hydrated. Make sure to drink plenty of water throughout the day to keep yourself hydrated and healthy. Staying hydrated will help to loosen secretions and allow you to more easily spit up the mucus produced by your respiratory system.

  • Use a humidifier or take a warm bath.  Warm, humid air can open your airways and make breathing easier. If you have a humidifier, use it to make your home environment more comfortable. If not, consider taking a warm bath or drinking a warm beverage.

  • While you’re sick, limit your contact with other people. Close contact with people can spread the bacterial or viral infections that cause pneumonia. While you’re sick, it’s best to limit your contact with family and friends to avoid spreading your infection.

  • Keep in touch with your healthcare provider. It’s important to keep in contact with your healthcare provider, even after you start to feel better. Your healthcare provider may suggest that you get a chest X-ray to check that your infection is gone after treatment with antibiotics and/or other medication.

Recovering from pneumonia can take anywhere from a few days to several weeks. You may still feel tired even after the other symptoms of pneumonia disappear. To make sure your symptoms don’t come back, take it step by step and don’t rush your recovery. 


There are several steps that you can take to reduce your risk of developing pneumonia, from vaccination to making changes to your habits and lifestyle to strengthen your immune system and improve your overall health.

Although vaccines won’t provide protection against every type of pneumonia, pneumococcal vaccination can help to prevent many cases of pneumonia.

Pneumococcal vaccination is important for people with a high risk of developing pneumonia, such as people aged under five or over 65 years, people with serious health conditions and tobacco smokers.

According to the CDC, one or more doses of the pneumococcal conjugate vaccine provides protection against pneumococcal pneumonia for approximately 45 percent of adults aged 65 years or older.

If you’re in a high-risk group for pneumonia and want to get vaccinated, talk to your healthcare provider. To find places close to you that offer vaccination, check with your state health department or use this vaccine finder provided by the Department of Health and Human Services.

Several other vaccinations can also reduce your risk of developing pneumonia. Since many cases of pneumonia develop after having influenza (flu), getting an annual flu vaccine is an easy way to reduce your risk of developing pneumonia following the flu.

You can find more information about the flu vaccine, as well as locations near you that offer vaccination, in this guide from the CDC.

The Haemophilus influenzae type b (Hib) vaccine is recommended for all children under five years of age in the United States. This bacteria can cause illnesses such as pneumonia and meningitis. Getting your child vaccinated will reduce their risk of developing these illnesses. 

More information about the Hib vaccine and options for getting your child vaccinated can be found in this vaccine information statement from the CDC

As well as getting vaccinated, making certain changes to your habits and lifestyle can lower your risk of developing pneumonia:

  • Quit smoking. Smoking damages your lungs, reducing your level of protection from harmful bacteria and viruses that cause pneumonia and numerous other respiratory illnesses.

    If you smoke cigarettes or use other tobacco products, consider quitting. Not only will quitting lower your risk of developing pneumonia — it can also reduce your cancer risk and improve your cardiovascular health.

  • Wash your hands frequently. Washing your hands often reduces your exposure to bacteria and viruses, including those that can cause pneumonia. This guide from the CDC explains how to wash your hands to protect yourself and others from germs.

  • Practice good lifestyle habits. Eating a healthy diet, exercising regularly and getting enough sleep all play a role in strengthening your immune system, making you less susceptible to illnesses such as pneumonia.

  • If you get sick, pay close attention to your symptoms. Pneumonia often develops after respiratory infections such as influenza (flu) and the common cold. If you’re sick, pay close attention to symptoms that linger for longer than a few days and talk to your healthcare provider if the symptoms appear to not be going away.

  • If you have a compromised immune system, talk to your healthcare provider. If you have any condition that affects your immune system, such as HIV/AIDS or cancer, talk to your healthcare provider to make sure you’re as protected as possible against pneumonia.

Talk to a Healthcare Professional About Pneumonia

If you think that you might have pneumonia, it’s important to talk to a healthcare professional. Pneumonia can lead to severe complications and, in certain cases, become a life-threatening condition. 

Consult with a licensed healthcare provider now to discuss your symptoms and learn more about what you can do to treat and manage pneumonia. 

If appropriate, the provider can write you a prescription on the spot and send it directly to a local pharmacy of your choice, allowing you to get the relief you need fast, all without having to go to a doctor’s office. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

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