Here's what to know about each one—including treatment options.

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It's easy to assume all cases of pneumonia are created equal, but there are actually several different types of the infection—and knowing the kind of pneumonia that you have can be crucial in order to get you the proper care you need.

"The different types of pneumonia can sometimes require very different treatments," Thomas Monaco, MD, assistant professor of medicine-pulmonary at the Baylor College of Medicine, tells Health. "For example, one group of bacteria that causes pneumonia may not respond to the same antibiotic as another group, and antibiotics will not help at all if the cause of the pneumonia is due to a virus or some of the more uncommon causes of pneumonia."

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Credit: Getty Images / Jo Imperio

Shweta Sood, MD, MS, a pulmonologist at Penn Medicine, agrees. "For us, it's really helpful to know the type because it influences our therapies for that specific patient, including how aggressive they should be," Dr. Sood tells Health. And once your doctor can figure out the type of pneumonia you have, they can get you the right treatment to help you feel like yourself again sooner. 

But while you're probably familiar with what pneumonia is, you might be a little unsure of the details. Quick recap: Pneumonia is an infection of the tiny air sacs in the lungs, called alveoli, according to the Centers for Disease Control and Prevention (CDC), and it can cause mild to severe illness in people of all ages. 

Again, there's not one type of pneumonia, and each form has a slightly different cause. Here's a breakdown of the different types of pneumonia, according to experts.

Bacterial pneumonia

Bacterial pneumonia is pneumonia that's caused by bacteria—most commonly, Streptococcus pneumoniae. This is a bacteria that normally lives in your upper respiratory tract that can make its way down into your lungs and cause an infection, Raymond Casciari, MD, a pulmonologist at St. Joseph Hospital in Orange, Calif., tells Health. Bacterial pneumonia infects more than 900,000 Americans each year, according to the American Lung Association (ALA), and you can develop this form of pneumonia on its own or after you've had a virus, like the cold or flu. 

Streptococcus pneumoniae isn't the only type of bacteria that can lead to bacterial pneumonia—Dr. Casciari lists off Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila as other possible causes. 

"We have very good and specific antibiotics to treat bacterial pneumonia," Dr. Sood says. "We need to first identify the bacteria and use the antibody that's specific for that bacteria."

Viral pneumonia 

Viral pneumonia is caused by a virus, and there are plenty that can make you sick, Medline Plus says. Those include:

  • Respiratory syncytial virus (RSV)
  • Influenza virus
  • Parainfluenza virus
  • Adenovirus
  • Measles virus
  • Coronaviruses, including SARS-CoV-2, the virus that causes COVID-19

Unfortunately, antibiotics don't treat viral pneumonia, but there are some medications that may help if the infection is caught early, including antiviral drugs and corticosteroids, to try to help reduce inflammation, Dr. Casciari says. In more severe cases, you may need supplemental oxygen as a treatment. For milder cases of the illness, though, Dr. Sood says that your doctor will probably recommend that you rest at home and get plenty of fluids. 

You do have the option, however, to prevent some of the viruses that can cause pneumonia—the flu, measles, and COVID-19 all have vaccines available to prevent severe illness.

Fungal pneumonia

Fungal pneumonia isn't common in most parts of the US, and people are usually infected when they breathe in certain fungal spores, Dr. Casciari says. However, there is a condition called valley fever, which is a type of fungal pneumonia caused by the fungus Coccidioides, which lives in soil in the southwestern U.S.

Fungal pneumonia is usually more of a concern for people with weakened immune systems, like those who have diabetes, AIDS, or cancer, Marc Sala, MD, a pulmonologist at Northwestern Medicine, tells Health

Treatment usually involves antifungal medications like fluconazole, Dr. Casciari says.

Walking pneumonia

To be fair, the term "walking pneumonia" isn't necessarily a true medical diagnosis, but doctors (and many people) know what the phrase means

"What it implies is that whatever the cause of your pneumonia is, it's not severe enough to put you in bed," says Dr. Casciari. Dr. Sood echoes that statement, saying that, with walking pneumonia, you can feel sick, "but you're still able to do most activities."

Walking pneumonia can come from any of the main causes of pneumonia—bacterial, viral, or fungal—according to Dr. Casciari. But the CDC says it's most commonly the result of an infection by the Mycoplasma pneumoniae bacteria, which causes milder infections in the respiratory system.

Chemical pneumonia

Chemical pneumonia is caused by a toxin that you inhale, Reynold A. Panettieri, Jr., MD, professor of medicine at Rutgers Robert Wood Johnson Medical School and director of the Rutgers Institute for Translational Medicine & Science, tells Health. "Classic chemical pneumonia was caused by chlorine gas, which was used as a weapon in World War I," he says. But it's possible to get chemical pneumonia from other things, including by accidentally breathing in large amounts of fumes from cleaning supplies, pool equipment, or even air fresheners, if they're sprayed directly into someone's airways, Dr. Casciari says. "These things can physically irritate the lungs," he explains. 

For treatment, you'll first need to get away from the source that's injured you. "If your eyes are burning, your lungs are, too," Dr. Casciari says. Then, doctors will usually provide supportive care until your lungs can heal themselves. "That might involve supplemental oxygen, fluids, and even mechanical ventilation," Dr. Casciari says.

Aspiration pneumonia

Aspiration pneumonia is an infection that can happen when you accidentally inhale substances into your lungs, like your own stomach acid or food particles. That causes inflammation and "sometimes this injury can be followed by a secondary bacterial infection," Dr. Monaco says.

This condition is more common in people who have a brain injury, neurological disorder, trouble swallowing, or have used drugs or alcohol—anything that can interfere with the gag reflex that would help keep these substances out of the lungs, Dr. Casciari says.  

Treatment for aspiration pneumonia varies: "If the aspiration is small in amount and there is no sign of a secondary infection, we usually treat it supportively with oxygen and prevention of further aspiration," Dr. Monaco says. "Most patients recover fully." If there's a lot of stuff in your airways, you may need a breathing tube and a procedure called a bronchoscopy to help remove everything, he says, adding that antibiotics may also be needed.

How you get pneumonia matters, too

The way you get pneumonia can generally be classified into two camps: Community-acquired pneumonia and health care–acquired pneumonia.

"Community-acquired pneumonia is someone living their normal life, who gets sick and is diagnosed with pneumonia," Dr. Sood says. "Most of the time, they can be treated safely with rest at home and antibiotics."

But health care–acquired pneumonia is different. "That's a term we use for patients that are in the hospital or are going to hospital-like settings and get pneumonia," Dr. Sood says. "They tend to get infected with bugs that require more aggressive therapy and antibiotics."

A more common way that someone gets health care–acquired pneumonia is from the use of a ventilator, Dr. Panettieri says. "With a ventilator, the tube goes through your windpipe so you can still maintain oxygen to your heart and brain," he explains. "But that tube, which is a foreign object, can be a conduit for any bacteria to get directly into the lungs." This is a big concern for doctors with ventilator use, since people who are on a ventilator are often sick to begin with. "The mortality of that is very high," Dr. Panettieri says. 

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