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Symptoms of Stomach Flu

Gastroenteritis is an intestinal infection accompanied by watery diarrhea, abdominal cramps, nausea or vomiting, and sometimes fever. The most common way to develop viral gastroenteritis —called stomach flu — is through contact with an infected person or by ingesting contaminated food or water. If you're otherwise healthy, you'll likely recover without complications. But for infants, older adults and people with compromised immune systems, viral gastroenteritis can be deadly. There's no fully effective treatment for viral gastroenteritis, so prevention is the only key. In addition to avoiding food and water that may be contaminated, thorough and frequent hand-washings are your best choices.


The signs and symptoms of stomach flu may vary depending on the cause.

  • The primary symptom of stomach flu is diarrhea.
  • Nausea, vomiting, and some abdominal cramping may accompany the diarrhea.
  • Mild fever, chills, headache, and muscle aches along with feeling tired may occur in some individuals with viral gastroenteritis.
  • Vomiting is occasional.
  • Symptoms usually last about 2 to 5 days and then begin to resolve with viral gastroenteritis.
  • Stomach flu shares many of the symptoms as viral stomach flu, but in some individuals, bacteria may cause bloody diarrhea.

Symptoms may occur in some individuals with either viral or bacterial stomach flu. Symptoms also may be seen with other causes of stomach flu (drugs, food allergies, toxins), for example:

  • Abdominal pain
  • Weight loss
  • Muscle aches and pains
  • Headache
  • Severe gastroenteritis means the person has signs of dehydration; this is a medical emergency.

Symptoms in children

Children with gastroenteritis or stomach flu usually have diarrhea, but may have other symptoms like:

  • Diarrhea
  • Refusing to eat or drink or are very thirsty
  • Weight loss
  • Lethargy
  • Bloody diarrhea


There are many ways gastroenteritis can be spread:

  • Contact with someone who has the virus
  • Contaminated food or water
  • Unwashed hands after going to the bathroom or changing a diaper
  • The most common cause of stomach flu is a virus. It can be caused by many different kinds of viruses.

Rotavirus is the world's most common cause of diarrhea in infants and young children. Norovirus is the most common cause of serious gastroenteritis and also foodborne disease outbreaks in the U.S.

When to see a doctor

If you're an adult, call your doctor if:

  • You're not able to keep liquids down for 24 hours
  • You've been vomiting for more than two days
  • You're vomiting blood
  • You're dehydrated
  • You notice blood in your bowel movements
  • You have a fever above 104 F (40 C)

Your doctor will likely diagnose gastroenteritis based on the symptoms that you have, a physical exam and sometimes on the presence of similar cases in your community. A rapid stool test can detect rotavirus or norovirus, but there are no quick tests for other viruses that cause gastroenteritis. In some cases, your doctor may have you submit a stool sample to rule out a possible bacterial or parasitic infection. Most commonly, there's no specific medical treatment for stomach flu. Antibiotics aren't effective against viruses, and overusing them can contribute to the development of antibiotic-resistant strains of bacteria. Treatment initially consists of self-care measures.