Diarrhea and other gastrointestinal symptoms are less common but possible if you have pneumonia, or are taking medications for this lung infection.

Pneumonia is an infection that causes inflammation in the air sacs of one or both lungs. The inflammation leads to the build-up of fluid within the lungs, making it hard to breathe.

Shortness of breath is just one of the symptoms of pneumonia. Other common symptoms include:

  • cough
  • fever
  • chills
  • chest pain
  • fatigue and confusion

Less commonly, pneumonia can affect the gastrointestinal (GI) tract, leading to GI symptoms like diarrhea or constipation. According to one older study from 2005, diarrhea was reported 24% of the time in a group of 1,812 participants with community-acquired pneumonia.

Read on to learn more about the connection between pneumonia and diarrhea.

Pneumonia can sometimes cause inflammation in other parts of your body, including the GI tract. That’s why it can less frequently cause other symptoms, including diarrhea.

Additionally, diarrhea can occur alongside pneumonia due to side effects of pneumonia medications and due to dehydration caused by pneumonia.

Due to inflammation of the GI tract

Pneumonia can trigger an inflammatory response in your body that can affect various organs, including disrupting your body’s GI tract function. This can change how much bodily fluid is sent to your GI tract to assist in bowel movements, leading to diarrhea.

Additionally, GI tract inflammation can disrupt the balance of your gut microbiome, where millions of bacteria live. Changes to the composition of your gut microbiome can contribute to diarrhea.

Due to dehydration

One of the common symptoms of pneumonia is fever. Having a fever means you may sweat more, and this leads to increased loss of bodily fluids. If you are losing more fluids than you are taking in by drinking plenty of water, you may become dehydrated. Dehydration can lead to both diarrhea and constipation.

While the reverse relationship is better understood (diarrhea leading to dehydration), dehydration can cause diarrhea if it stimulates your body’s fluid secretion, leading to watery stools.

Medication side effect

Some medications used to treat pneumonia can cause GI side effects including diarrhea. This occurs due the alteration of the balance of gut bacteria in your body’s gut microbiome.

Pneumonia medications that can cause diarrhea include:

Generally speaking, diarrhea associated with pneumonia typically resolves within a few days after starting treatment for pneumonia.

The total duration depends on several factors, including the cause of pneumonia, your treatment plan, and your overall health.

Drinking plenty of water is important to counteract the effects of fluid loss through diarrhea.

In addition to diarrhea, pneumonia or medications used to treat it may cause other GI symptoms, such as:

  • nausea
  • vomiting
  • abdominal pain
  • loss of appetite
  • feeling of bloating, fullness, or stomach discomfort

It’s important to pay attention to your symptoms and medication side effects. Contact the medical professional treating you if your diarrhea lasts more than a few days after starting treatment for pneumonia, or if it increases after you start taking medications for the condition.

It’s also important to continue drinking plenty of water to replenish your body’s fluids.

Diarrhea and other gastrointestinal symptoms are less common but possible if you have pneumonia. This can be due to changes in your gut microbiome, dehydration, or the medications you are taking.

The severity of your symptoms can vary depending on your overall health, your age, and the underlying cause of the pneumonia.

Let your doctor know if the diarrhea persists more than a few days after starting treatment, or if diarrhea caused by pneumonia medications is affecting your day-to-day life.