At the most basic level, pneumonia is an infection of the lungs that causes inflammation and fluid buildup in the lungs' air sacs or alveoli, according to the Centers for Disease Control and Prevention <\/a>(CDC). It can cause mild to severe illness in people of all ages. While you're more likely to get pneumonia if you're a smoker or have underlying medical conditions like diabetes or heart disease, any person of any age can get pneumonia, Raymond Casciari, MD, a pulmonologist at St. Joseph Hospital in Orange, California, tells Health<\/em>.<\/p>\n In order to remain your healthiest and stay pneumonia-free (at least as much as humanly possible), it's helpful to arm yourself with all the facts about pneumonia—and that includes what most commonly causes the lung infection. Here, experts explain the three main causes of pneumonia, and what you need to know about each. <\/p>\n RELATED: Double Pneumonia Is an Infection in Both Lungs—Here's What to Know, According to Doctors<\/a><\/strong><\/p>\n Bacterial pneumonia is usually caused by Streptococcus<\/em> pneumoniae, <\/em>which lives in the upper respiratory tract, Dr. Casciari says. "This is the most common cause of pneumonia," he adds. <\/p>\n You can develop bacterial pneumonia as a complication of a viral infection, like the cold or flu; due to aspirating or inhaling fluid like saliva or vomit<\/a><\/a>; or you can just develop it on its own. "It used to be thought that the lungs were a sterile environment, devoid of bacteria. We now know that this is not true and that the lungs are 'colonized' by bacteria that are harmless under ordinary circumstances," Marc A. Sala, MD, a pulmonologist and assistant professor of medicine at Northwestern Medicine, tells Health<\/em>. But, in some situations, like after a viral infection that disturbs the balance of bacteria in your lungs, you can develop bacterial pneumonia, he says. <\/p>\n While Streptococcus<\/em> pneumoniae <\/em>is the main cause of bacterial pneumonia, it's not the only cause, says Dr. Casciari. Other types of bacteria known to cause pneumonia, per the US National Library of Medicine's MedlinePlus resource, include:<\/p>\n Bacterial pneumonia is usually treated with oral antibiotics, Dr. Casciari says. But, in more severe cases, a patient may be given IV antibiotics, breathing treatments, or oxygen therapy, MedlinePlus<\/a> says. Also worth noting, per the CDC<\/a>: The pneumococcal vaccine can help lower your risk of contracting bacterial pneumonia from Streptococcus<\/em> pneumoniae.<\/em><\/p>\n RELATED: What Is Aspiration Pneumonia? Doctors Explain Symptoms, Causes, and Treatments<\/a><\/strong><\/p>\n There are a lot of viruses that can lead to viral pneumonia. Respiratory syncytial virus (RSV) is the most common cause of pneumonia in children, but the influenza virus and SARS-CoV-2, the virus that causes COVID-19<\/a>, are the main causes of pneumonia in adults, Dr. Casciari says. MedlinePlus says the common cold<\/a> also has the potential of leading to pneumonia.<\/p>\n "The typical way that one develops pneumonia is by being exposed to the droplets or aerosols of someone who has an active infection, resulting in inflammation and an immune response, which we then refer to as pneumonia," Dr. Sala says. Viral pneumonias can also have a secondary bacterial infection, Dr. Casciari says. <\/p>\n Treatment for viral pneumonia usually involves the use of an antiviral treatment like oseltamivir (Tamiflu) or remdesivir, Dr. Casciari says. And just like with bacterial pneumonia, people with severe cases may need supplemental oxygen or breathing treatments. <\/p>\n Some vaccines can help lower your risk of developing viral pneumonia, including the flu vaccine<\/a> and COVID-19 vaccine<\/a>, Dr. Casciari says. <\/p>\n![\"Pneumonia-Causes-GettyImages-1126697992\"](\"https:\/\/imagesvc.meredithcorp.io\/v3\/mm\/image?url=https%3A%2F%2Fstatic.onecms.io%2Fwp-content%2Fuploads%2Fsites%2F12%2F2021%2F09%2F15%2FPneumonia-Causes-GettyImages-1126697992-2000.jpg\")
Pneumonia-Causes-GettyImages-1126697992<\/span> —and that doesn't include people who were diagnosed by their primary care physician.<\/p>\nBacteria <\/h2>\n
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Viruses <\/h2>\n