Walking pneumonia: The "mild" illness that can still pack a punch

If you’re among the people who’ve heard the term “walking pneumonia” but don’t quite know what it means, join the club. There’s nothing mysterious about walking pneumonia — just a fair amount of variation in how it shows up.

Unlike “classic” pneumonia, the lung infection is often mild enough that people remain on their feet — hence the “walking” part of the term. But even if you don’t feel sick enough to stay in bed, it’s still pneumonia — and can turn serious, says Dr. Gerald Weinhouse, clinical director of ambulatory services for the Division of Pulmonary and Critical Care at Harvard-affiliated Mass General Brigham.

“It’s definitely not harmless, especially if you have a weak immune system or some other major medical illness,” says Dr. Weinhouse, also the medical director of Respiratory Care Services at Brigham and Women’s Hospital and Dana-Farber Cancer Institute.

 “It can start relatively mild, but get worse,” he adds. “No pneumonia is okay — it should all be addressed, whether you talk to your doctor over the phone or get an x-ray or go to the hospital.”

What causes walking pneumonia, and is it contagious?

Cases of walking pneumonia are most commonly caused by the bacteria Mycoplasma pneumoniae and Streptococcus pneumoniae, and by respiratory viruses, Dr. Weinhouse says. (Those viruses can include the ones that cause flu and COVID-19.)

Anyone can get walking pneumonia, since the germs causing it are easily spread, particularly in places such as dormitories or military barracks. “If you’re in the vicinity of someone coughing and they happen to pass it, you can get it, even with a perfectly healthy immune system,” he says.

That said, some people are more prone to developing a worse case. That’s especially true for older adults and people with chronic health problems, including people who smoke and those with lung conditions, heart disease and diabetes.

What are the symptoms of walking pneumonia?

Walking pneumonia symptoms are often subtle at first and can include

• sore throat
• fatigue
• mild fever or chills
• headache
• runny or stuffy nose.

But as the illness progresses, walking pneumonia may also include

• persistent cough
• chest discomfort
• shortness of breath with exertion.

The latter symptom is how people can tell it’s more than a bad cold. “If you’re short of breath, that’s not a cold — it’s in your chest,” he says. “Chest pain is another symptom you don’t get with a cold.”

How long does walking pneumonia last?

What might surprise you is that these symptoms — despite their overall mild nature — can linger. The cough, which is rarely “wet” or “productive” (one that brings up mucus), can persist for weeks, Dr. Weinhouse notes. Some people can also feel exhausted for that long, and frequent coughing can disrupt sleep and make it difficult to exercise.

“The risk is in not knowing when to go seek help,” Dr. Weinhouse says. “If you don’t feel that bad and it doesn’t affect your ability to function normally, it’s probably walking pneumonia. But if you have a fever, cough — and, certainly, shortness of breath — you should seek help immediately.” (See “Warning signs to watch.”)

How is walking pneumonia diagnosed?

An x-ray is usually all that’s needed to diagnose walking pneumonia, though sometimes mild cases don’t show up on imaging, Dr. Weinhouse says. In that case, doctors may base the diagnosis on symptom pattern and results from a physical exam. Testing for flu or COVID-19 can also determine if the cause is viral, guiding treatment.

Walking pneumonia treatment typically involves antibiotics or antiviral medications, as well as rest, fluids, and other supportive measures. With treatment, any fever should quickly abate. You should also start to feel noticeably better within two to three days. “But I tell patients not to be surprised if you’re not back to normal for four to six weeks,” Dr. Weinhouse says.

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