Viral vs. Bacterial Pneumonia: What's the Difference?

Viral and bacterial are two more common types of pneumonia, an infection within your lungs. “Both forms of pneumonia are very similar,” Dawn Turner, DO, attending physician at MedPost, Detroit Medical Center’s urgent care partner, told Health.

So does it matter which one you have?

Doctors will answer that question with a resounding yes, since treatment—and often, the severity of the illness—differs significantly. See what else is different between viral and bacterial pneumonia and the best ways to ward them off.

What Causes Pneumonia?

That depends on what type of pneumonia it is. All sorts of viruses—from the common cold to influenza—can lead to viral pneumonia, which is pretty contagious, Roger Lovell, MD, infectious disease specialist at Piedmont Athens Regional Medical Center, told Health. It passes easily between coworkers, spouses, friends, and fellow commuters.

The good news? “Most cases of viral pneumonia are mild,” notes the National Heart, Lung, and Blood Institute (NHLBI). Typically, you’ll improve in a few weeks.

Bacterial Pneumonia

Bacterial pneumonia often occurs after another illness, like the cold or the flu. However, most of the time, the bacteria behind bacterial pneumonia do not spread from person to person, said Dr. Lovell.

That's true for the number one cause of bacterial pneumonia: a type of bacteria called Streptococcus pneumoniae, which is found in many people’s throats naturally, generally without causing harm, said Dr. Lovell. The exception: "If you are not healthy or have problems with your immune system or have conditions that make it harder to fight off bacteria, then you are more susceptible to these bacteria, and it can lead to pneumonia."

Fungal Pneumonia

Along with viral and bacterial pneumonia, there's a third type worth knowing: fungal. This variant is far more rare and generally seen only in people with a weakened immune system due to certain conditions. Other types of pneumonia to note: necrotizing pneumonia (a rare but quite serious type of bacterial pneumonia) and cryptogenic organizing pneumonia (another rare disease, with unknown causes, that’s typically treated with steroids).

Walking Pneumonia

You may also have heard of walking pneumonia, which the American Lung Association describes as a “non-medical term” for a case of pneumonia with mild symptoms; you can walk around without realizing you’re ill.

How To Prevent Pneumonia

“Good hygiene and health practices will help you from contracting most infections,” Turner said.

You probably already know the drill here: Wash your hands frequently, avoid sneezers and their trail of tissues, and clean often touched surfaces—elevator buttons, handles, doorknobs—where germs can linger.

And keep your immune system strong with a nutritious diet, lots of water, and adequate sleep, Turner added.

Vaccines are also an effective preventive measure. Get the flu vaccine annually—influenza is unpleasant on its own but can also lead to pneumonia. “Get the pneumococcal vaccine if you are 65 years or older,” Turner advised; the vaccine, which protects against bacterial pneumonia, is also recommended for cigarette smokers and younger people with certain medical conditions.

Viral and Bacterial Pneumonia Symptoms Are Similar

If you have pneumonia—either bacterial or viral—you’ll typically have a cough that brings up sputum, fever, shortness of breath, and chest pain when you cough or take a deep breath, said Kimberly Brown, MD, MPH, an emergency medicine doctor in Memphis, Tennessee.

“It can be difficult to tell by symptoms alone whether you have viral or bacterial pneumonia,” said Dr. Brown.

But there is one potential tip-off that it’s bacterial and not viral. “Generally, bacterial pneumonia causes the more severe symptoms,” Turner said.

How To Treat Pneumonia

Along with a physical exam, your healthcare provider may take a sputum culture, chest X-ray, and blood work to determine if you have a viral or bacterial form of pneumonia, Turner said.

Your diagnosis is essential since it helps determine treatment. "If you have viral pneumonia, I wouldn't prescribe to you an antibiotic," said Dr. Brown.

That's for three important reasons. First, antibiotics simply don't work to treat viruses. And, they can lead to unpleasant side effects (possibly even more uncomfortable than the initial symptoms). Finally, unnecessary use of antibiotics might make them ineffective when you actually need them for treatment, said Dr. Brown. "We always strive to give the right treatment to the right patient at the right time."

Instead of antibiotics, if you have a viral form of pneumonia, your healthcare provider will recommend antiviral agents or over-the-counter medications to ease your symptoms, said Dr. Lovell. Tylenol can bring down your fever, for instance, while an expectorant thins out mucus so you can cough more productively.

A Quick Review

Pneumonia is a serious illness. While sometimes—as with walking pneumonia—the symptoms are pretty mild, the disease can be life-threatening. And while bacterial pneumonia is typically the more worrisome type, with more severe symptoms, viral can also be quite serious as well, Turner noted: “Viral pneumonia, especially in the very young, very old, and immunocompromised patients, can also become severe and may even warrant hospitalization.”