Stomach flu, or viral gastroenteritis, is an infection of the intestines caused by several types of viruses, according to the National Digestive Diseases Information Clearinghouse. The stomach flu is not the same as influenza, or the common flu, as this stomach flu does not affect the respiratory system and is caused by different viruses. Viral gastroenteritis is the second most common illness in the United States, and most people who get the disease recover well. But the disease can be severe in patients who are very young, very old or have very weak immune systems.
Diarrhea
Diarrhea is one of the most common symptoms of stomach flu, reports the Mayo Clinic. The virus causes an inflammation of the stomach and intestines that prevents proper absorption of food. Furthermore, the irritation caused by the virus can add to the diarrhea. Diarrhea in stomach flu cases is described as watery and typically nonbloody. Patients with diarrhea caused by viral gastroenteritis should make sure they are drinking adequate fluids in order to maintain proper hydration.
Nausea and Vomiting
Viral gastroenteritis can cause nausea and vomiting, according to Medline Plus, a National Institutes of Health, website. The virus aggravates the tissues of the digestive system. In rare cases patients may vomit blood. Those who are vomiting frequently or vomiting blood should seek medical care.
Abdominal Discomfort
Common symptoms of the stomach flu virus are abdominal pain and cramping, according to the National Digestive Diseases Information Clearinghouse. Patients will develop these symptoms four to 48 hours after infection, and they last for one to two days. If the symptoms last for more than a few days, or if the pain worsens, medical treatment may be necessary.
Fever and Chills
Stomach flu virus, like most other viruses, can cause systemic symptoms such as fever and chills, according to the Mayo Clinic. Fever, night sweats, clammy skin and excessive sweating often accompany viral gastroenteritis. These symptoms are due to the body's immune response to the infection. Children with a fever greater than 102 degrees Fahrenheit and adults with a fever of more than 104 degrees should seek medical attention.
Poor Feeding
Infants who develop viral gastroenteritis can manifest signs of poor feeding, according to Medline Plus. Infants will be unwilling to feed as frequently as normal and may regurgitate any food.
Fatigue
In some cases of stomach flu patients may experience mild to extreme fatigue, according to the National Digestive Diseases Information Clearinghouse. The stomach flu can be caused by different types of viruses, and one type, called the calicivirus, can cause patients to feel very tired and lethargic. This fatigue usually lasts one to two days, but if it persists for more than a week, a doctor's assistance may be required.
