What Causes Vomiting and Diarrhea without Fever? Gastroenterologist Explains.

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Summary (what you need to know):

  • viral gastroenteritis (stomach flu) is the most common cause of acute vomiting and diarrhea.
  • The vomiting and diarrhea can be with or without fever. Fever is often low-grade when it occurs.
  • Other infections such as parasites and bacterial can also cause diarrhea and vomiting without fever.
  • Other causes include food allergy, food intolerance, medications, and toxins.

1. Viral Gastroenteritis.

Viral gastroenteritis (stomach flu) is responsible for most cases of acute vomiting and diarrhea. In addition, stomach viruses often cause diarrhea with vomiting with low-grade or absent fever.

The leading causes of viral gastroenteritis are:

  • Norovirus: The most common cause of acute onset vomiting and diarrhea.
  • Rotavirus: The second common cause of viral gastroenteritis, It was the commonest cause until the introduction of the Rotavirus vaccine in 2006 (reference)
  • Others: astrovirus, sapovirus, and adenoviruses are responsible for less than 10% of the cases of viral gastroenteritis (reference).

Norovirus and Rotavirus are responsible for about 90% of the cases of viral gastroenteritis.

How do you get infected?

Stomach viruses often spread vial the fecal-oral root (touching contaminated surfaces or dealing with an infected person).

Also, these viruses can cause foodborne illnesses (food poisoning). Norovirus alone is responsible for about half of the cases of food poisoning outbreaks (reference).

Symptoms of viral gastroenteritis:


  • Sudden onset of loose or watery diarrhea (more than three motions per day).
  • Sudden onset of vomiting (it is more severe in younger ages. Vomiting is more common with gastroenteritis because the stomach viruses cause gastroparesis (decreased motility of the stomach).
  • The vomiting and diarrhea are without fever or with low-grade unnoticeable fever.
  • Nause without vomiting can also be present.
  • Fatigue and muscle aches.
  • Severe lower abdominal cramps that partially improve after bowel motions.

The course of symptoms:

  • The vomiting and diarrhea start suddenly.
  • They typically improve within one to three days.
  • In more than 99% of cases, signs don’t exceed one week.
  • If the vomiting and diarrhea (with or without fever) last for more than a week, you should see a doctor even if the symptoms are mild.

The best treatment for viral gastroenteritis.

No medications can kill stomach viruses. Instead, they are self-limiting infections. As a result, the vomiting and diarrhea often resolve spontaneously within a couple of days.

We aim by treatments to prevent and treat its complications. For example:

  • Eating bland, easy-to-digest food such as BRAT diet (Bananas, Rice, Apple sauce, and Toast).
  • Avoid foods that may aggravate vomiting and diarrhea, such as fatty foods, spicy foods, caffeine, alcohol, and fast foods.
  • Staying hydrated is the most crucial step in the prevention of complications of stomach flu.
  • In severe cases, over-the-counter anti=emetics, antispasmodics, probiotics, or anti-diarrheal can be used. However, most people will not need them as the condition is self-limiting.

Important: Stomach viruses vomiting and diarrhea without fever. However, in most cases, you may have a low-grade fever that is not felt. Suspect low-grade fever if you have malaise and muscle aches.

You can also confirm fever by using a thermometer. You will notice a minor elevation of your baby’s or your temperature.

2. Some Types of food poisoning.

Food poisoning (foodborne illness) refers to any disease caused by food. The most prevalent pattern of food poisoning is contamination with stomach viruses.

As we mentioned before, Norovirus alone is responsible for about 50% of the cases of food poisoning. Symptoms of food poisoning often appear anywhere between a few hours to several days after ingesting the offending food.

Common food poisoning sources and organisms are in the below:

Food poisoning sourcePossible organisms (Incubation Period)
1. Raw seafood* Norovirus (1-2 days).
* Vibrio species (1-3 days).
* Hepatitis A (15-50 days).
2. Raw eggs* Salmonella (1-3 days)
3. Undercooked meat or poultry.* Salmonella (1-3 days).
* Campylobacter (1-3days).
* E. Coli (STEC), (3-4 days).
* Clostridium perfringens (8-16 hours).
4. Unpasteurized Milk or juice.* Salmonella (1-3 days).
* Campylobacter (1-3days).
* E. Coli (STEC), (3-4 days).
* Yersinia enterocolitica (4-6 days).
5. Unpasteurized soft cheeses* Salmonella (1-3 days)
* Campylobacter (1-3 days).
* E. Coli (STEC), (3-4 days).
*Yersinia enterocolitica. (4-6 days).
* Listeria monocytogenes (1 day).
6. Homemade canned goods.* Clostridium botulinum (12 h-3 days).
7. Raw hot dogs, deli meat* Listeria monocytogenes. (1 day).

Diarrhea of food poisoning can be one of two types:

  • Watery diarrhea: often large volume, watery, NOT associated with fever.
  • Inflammatory diarrhea: often of small volume, with blood or mucus in stool, and associated with high-grade fever

Examples of food poisoning cause that can cause watery diarrhea without fever:

  • Norovirus.
  • Clostridioides (formerly Clostridium) difficile.
  • Clostridium perfringens.
  • Enterotoxigenic Escherichia coli.
  • Other enteric viruses (Rotavirus, enteric adenovirus, astrovirus, sapovirus).
  • Cryptosporidium parvum.
  • Listeria monocytogenes.
  • Cyclospora cayetanensis.

Learn More about food poisoning.

3. Food intolerance or allergy.

Food intolerance is a prevalent condition, affecting up to 20% of people. It can lead to vomiting and diarrhea without fever.

Food intolerance is difficulty digesting certain foods or drinks. At the same time, food allergy is an immune-mediated reaction to food. The differences and similarities are outlined in the below table.

Food intoleranceFood allergy
Affects 15-20% of the populationAffects nearly 2-5% of adults
Difficulty digesting certain types of food (not immune-mediated allergy).An immune-mediated reaction to certain foods or food components.
Causes acute attacks of vomiting and diarrhea without feverCan cause acute attacks of vomiting and diarrhea with or without diarrhea.
Intestinal symptoms: diarrhea, extensive gas, bloating, and abdominal pain, and sometimes vomiting.Intestinal symptoms are the same.
No extraintestinal symptomsExtraintestinal symptoms like rashes, urticaria, swollen lips or face, or severe life-threatening allergic reactions.
The severity of your symptoms is proportional to the amount you eat from the offending food.Even trace amounts of the offending food can produce severe symptoms.
Common offending foods:
  • Lactose intolerance (dairy products).
  • Fructose malabsorption.
  • Alcohol intolerance.
  • FODMAP intolerance (as with People with IBS).
Common offending foods: (examples)
  • Raw meat, seafood.
  • Nuts, peanut
  • Mustard.
  • Rice
  • Some vegetables and fruits.

4. Others.

Other less frequent causes of vomiting and diarrhea without fever include:

  • Toxins ingestion, such as lead poisoning.
  • Drug overdose.
  • Certain medications such as colon preparations, chemotherapy, and some antibiotics.
  • Stress and psychological disturbances can also lead to extreme gastrointestinal disorders, including vomiting and diarrhea without fever.
  • Endocrinal diseases such as diabetic ketoacidosis, carcinoid syndrome, hyperthyroidism, and others.
  • The early stage of appendicitis can also present with vomiting and diarrhea without fever. However, severe periumbilical or right lower quadrant pain is often present.

When to see a doctor for vomiting and diarrhea:

  • Extreme intolerable abdominal pain.
  • Persistent vomiting after drinking or eating anything for more than 12 hours.
  • Dry mouth and dry tongue (decreased saliva).
  • Extreme thirst.
  • Dizziness, lightheadedness, severe headache.
  • Fast heartbeats.
  • Confusion or lost consciousness.
  • Severe fatigue and weakness.
  • Peeing too little or concentrated (deep yellow) urine.
  • Bloody stool or rectal bleeding.
  • Prolonged symptoms (more than one week).
  • If Your age is above 65 years old.
  • Having co-existing diseases such as diabetes, HIV, etc.
  • If you have vomiting and diarrhea while you’re pregnant.