With prominent television personalities like Oprah Winfrey and Savannah Guthrie coming down with cases of pneumonia, their time in bed is an important reminder to know the symptoms of the serious illness and how to treat it.

Pneumonia is an infection in one or both lungs, sometimes causing them to fill with fluid or phlegm.

Common symptoms of pneumonia include chest pain with breathing or coughing, confusion, cough with phlegm, fatigue, fever with sweating or shaking, nausea, vomiting, and shortness of breath, according to the Mayo Clinic.

Many people mistake some of these symptoms for the common cold, like Winfrey said she did.

"I came back from overseas and I thought I had a cold — but it wasn't a cold," she said Monday on "The Ellen DeGeneres Show." But as she found out, the illness was nothing to sneeze at.

"I ended up in the emergency room and they said, 'You have pneumonia.' And I go home, and pneumonia is nothing to play with, y'all. It is very serious. And I was on antibiotics for a week and the antibiotics weren't working. And then I go back for another CT scan and they go, 'It's actually worse. You should see a lung specialist," Winfrey added.

Guthrie described her "misery" of dealing with the infection while calling in to her "Today" colleagues while she was out sick.

 "I really have never been so laid out flat," she said. "This fever is the thing. It's not a cold, it's like I just couldn't get the fever to break and so I've just been on round-the-clock medicine to keep the fever down. And I started getting this real bad cough."

The group says people should see a doctor when they experience difficulty breathing, chest pain, a persistent fever of 102 degrees or a persistent cough.

It is especially important for certain groups of people to seek medical attention. Adults older than age 65 and children younger than age 2 are at the highest risk.

Complications from contracting pneumonia include bacteria in the bloodstream, chronic cough and fluid build up around the lungs.

People can help prevent pneumonia by getting vaccinated, practicing good hygiene, eating healthy, avoiding smoking and getting exercise.

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