Your heart and lungs share a close relationship, each relying on the other to replenish your blood with oxygen, remove wastes, and move blood and nutrients around your body.

When one of these players is underperforming or damaged, the other is quickly affected.

Pneumonia is an infection in one or both lungs. The tiny air sacs (alveoli) that move gases like oxygen in and out of your blood fill with fluid or pus.

This article will explore how pneumonia can affect how well your heart works and what can happen if you already have heart disease and then develop pneumonia.

Coronary artery disease is the most common form of heart disease in the United States. It develops when cholesterol and other substances build up in your blood vessels — specifically the coronary arteries that supply blood to your heart.

Many things can lead to this buildup, including diet, lifestyle choices, and genetics.

The buildup of substances in your blood vessels is dangerous on its own since it can restrict blood flow to the heart and other body parts. But it’s even more serious when pieces of this buildup — called plaques — break off from the walls of your blood vessels.

When these pieces break off, they can travel to other areas of the body like the brain or heart, cutting off the blood supply to these organs resulting in a stroke or heart attack.

On its own, pneumonia is not a heart disease. It’s a lung infection caused by bacteria or viruses.

However, heart disease complications like congestive heart failure can cause a condition similar to pneumonia.

Certain types of heart failure can lead to pulmonary edema. In this case, the heart is too weak to effectively pump blood out to the body, so the blood backs up into the heart and eventually into the lungs.

As this backed-up blood builds up in the lungs, pressure in the blood vessels of your lungs increases, and it can cause fluid buildup in the alveoli.

This results in an effect similar to pneumonia, where these air sacs fill with fluid.

Pneumonia is an infection that can cause inflammation throughout the body. This inflammation can lead to other complications, including an increased risk that bits of plaque can break free from your vessel walls and lead to heart attack or stroke.

Even without existing coronary artery disease or plaque buildup, the body-wide inflammation that pneumonia triggers can cause its own problems.

Inflammation can interfere with the normal function of all kinds of systems in your body — especially the heart. This makes heart failure one of the most common complications of pneumonia.

About 30% of people hospitalized with community-acquired pneumonia develop heart failure and other cardiovascular problems, but the risk isn’t always immediate. Research indicates that the greatest risk of heart complications occurs in the month after a pneumonia diagnosis, and the risk can continue for up to a decade.

It can be difficult to tell when pneumonia is affecting your heart, as pneumonia and heart disease can share symptoms including:

Additional symptoms you may experience with pneumonia that are not as common with heart disease include:

  • chills
  • fever
  • a cough with mucus

Inflammation in response to a pneumonia infection has some of the greatest impact on your heart.

Although heart damage from pneumonia can happen in anyone, it affects people with preexisting heart disease the most.

Among people who develop pneumonia with preexisting heart failure, about 1.4% who are treated in the outpatient setting find their heart failure gets worse after pneumonia. That percentage increases to 24% in people with more severe pneumonia that requires hospitalization.

Aside from inflammation, some individual cardiac symptoms or complications that can develop after a bout with pneumonia include:

The relationship between pneumonia and cardiovascular disease goes both ways: Pneumonia can increase the risk of heart disease, and a history of heart disease can increase the risk of pneumonia.

One 2018 study found that people with cardiovascular diseases — heart failure in particular — are three times more likely than others to develop community-acquired pneumonia.

Generally, the best way to prevent problems like pneumonia and heart failure is to take care of your overall health.

This means:

People with heart disease are generally recommended to stay up-to-date on various vaccinations, too. This can prevent acute infection and its complications.

However, there may be little difference in mortality rates among people with heart failure and pneumonia who had been vaccinated against things like influenza and pneumonia.

With every heartbeat and every breath, your lungs and heart work in tandem. Infections and chronic diseases that affect one organ can affect the other.

Pneumonia can increase your risk of developing heart disease or having your existing heart disease worsen. Likewise, heart disease can increase your risk of developing several types of pneumonia.

Talk with your doctor about your overall health and how to avoid chronic heart disease and acute infections like pneumonia.

Vaccines are one part of the equation, but the best strategy involves other health and diet strategies, too.