What Causes Diarrhea and Fever? 4 Possible Conditions

Diarrhea and fever can leave you feeling pretty awful and wondering what causes diarrhea. Food poisoning symptoms and norovirus symptoms can both include fever and diarrhea.

Gastroenteritis (also known as the stomach bug or stomach flu), COVID-19, and other infections may also be to blame. In most cases, diarrhea and fever will resolve within a few days, but it’s important to see a healthcare provider if you become dehydrated or have a very high fever. 

1. Viral Gastroenteritis (Stomach Flu)

Whether you call it gastroenteritis, the stomach flu, a 24-hour bug, or norovirus, a stomach bug is a very common cause of fever and diarrhea. Gastroenteritis actually refers to the inflammation of your intestines, and it can be caused by a virus (like norovirus), a type of bacteria, or another pathogen (disease-carrying organism). 

Diarrhea is a primary symptom of gastroenteritis, while fever is slightly less common. Other symptoms include:

• Body aches
• Chills
• Nausea and vomiting
• Stomach pain
  

A stomach bug usually comes on suddenly and resolves within three days or so.

2. Food Poisoning

Diarrhea and fever are common food poisoning symptoms. Bacterial gastroenteritis is a type of food poisoning that occurs when you’re exposed to bacteria like Salmonella or Escherichia. coli (E. coli) in your food. Food poisoning can also be caused by other pathogens besides bacteria. 

Other symptoms of food poisoning include:

• Fever
• Nausea and vomiting
• Stomach pain and cramping

Food poisoning usually comes on suddenly. It can last for a few hours, or a few days depending on what type of germ caused the illness. 

3. COVID-19

Fever is one of the primary symptoms of COVID-19, and some people experience diarrhea with COVID too. Other symptoms include:

• Body aches
• Cough
• Loss of taste and smell
• Shortness of breath
• Sore throat
  

If you have COVID, you will notice that your symptoms start mild but build. This differs from other causes of fever and diarrhea, which often occur suddenly. 

4. Chronic Gastrointestinal Issues

Some chronic gastrointestinal issues can cause both diarrhea and fever. Colitis or diverticulitis can both cause these symptoms. If you regularly have diarrhea and a fever, talk with your healthcare provider. They may be able to identify a chronic GI issue that might be causing your symptoms. 

How to Tell What Causes Symptoms

It can be very difficult to tell whether diarrhea and fever are caused by a bacteria or virus. Either can cause diarrhea and fever when your intestines become inflamed (a condition known as gastroenteritis). 

In most cases, it doesn’t matter whether your symptoms are bacterial or viral, because the treatment will be the same. For example, you’ll need to try to manage the symptoms of diarrhea while avoiding dehydration.

If you need to see a healthcare provider, they may do tests on your stool (poop) that can help determine whether the illness is viral or bacterial. This can help them determine treatment, since antibiotics can fight bacterial infections like E. coli, but not viruses.

Tips to Feel Better

Usually, bouts of diarrhea and fever come on quickly but go away quickly too. You'll likely be feeling better within two to three days, if not fewer. These tips can help stop diarrhea and may make you feel better while you have it:

• Drink small, frequent sips of water: This can make you feel better and help prevent dehydration. 
• Eat small, bland snacks: Crackers, toast, bananas, rice, and applesauce are good idea to get nourishment when you have diarrhea.
• Use Tylenol, not ibuprofen: Common fever reducers like ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) can upset the stomach. Instead, opt for Tylenol and other non-NSAID fever reducers. 
• Try antidiarrheal medicines: Medications that contain bismuth subsalicylate or loperamide hydrochlorid (like Pepto-Bismol or Imodium) can help slow diarrhea down, so you don’t need the bathroom as frequently. 
• Rest: Rest is essential to help your body get over any illness, whether it’s food poisoning, COVID, or the stomach flu. Try to rest and sleep as much as possible while you recover.

When to Contact a Healthcare Provider

When you have diarrhea and fever, the biggest risk is dehydration. Learn to spot the signs of dehydration, and reach out to your healthcare provider right away if you notice any of them. You should also see a healthcare provider if you experience:

• Bloody diarrhea
• Changes to awareness or cognition
• Diarrhea for more than three days
• Dizziness
• Extreme weakness
• Fever that is over 102 degrees F or otherwise concerning
• Severe abdominal pain
• Weight loss
  

If you are pregnant and experience diarrhea and fever, give your healthcare provider a call as a precaution. Some conditions that cause diarrhea and fever, like listeria (a type of food poisoning), can be especially dangerous to pregnant people. Also, talk to your healthcare provider if you are older, immunocompromised, or were recently hospitalized.

Summary

It’s common to have diarrhea and fever together. This set of symptoms is often caused by viral or bacterial illness, including food poisoning. More rarely, it can also be a sign of chronic GI conditions. In most cases, diarrhea and fever will get better on their own within a few days. Watch carefully for signs of dehydration, and call your healthcare provider if you have blood in your stool, a fever over 102 degrees F, or any other concerning symptoms.