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Digestive health centre

Stomach flu and gastroenteritis

Stomach flu is also known as gastroenteritis, and has nothing to do with seasonal flu.

Gastroenteritis is irritation and inflammation of the stomach and bowel that is usually caused by a virus such as norovirus, and food poisoning.

Gastroenteritis usually causes mild symptoms in most people and clears up after a few days without any specific treatment.

Gastroenteritis can be more serious in babies, children and older people, and can also cause dehydration, which may require medical treatment or admission to hospital.

Those also at risk of stomach flu symptoms include pregnant women, infants, and undernourished and immune-compromised people.

What are the symptoms of gastroenteritis or stomach flu?

Symptoms of gastroenteritis or stomach flu include abdominal cramps, stomach pain, nausea, vomiting and diarrhoea. You may also have a high temperature, headache and swollen lymph glands, depending on the type of bug that causes it.

In severe cases of gastroenteritis, loss of bodily fluid can result in dehydration, a life-threatening condition that needs medical attention. Signs of dehydration include sunken eyes, light-headedness, increased thirst, dry or sticky mucus membranes in the mouth, lack of normal elasticity of the skin, decreased urine output and decreased tears.

You can avoid dehydration by continuing to drink fluids and trying to eat as normally as possible. Eating bland foods such as bananas, rice, apple sauce and dry toast is sometimes easier, and these are easily digested and less likely to irritate the sensitive gastrointestinal system.

What causes gastroenteritis or stomach flu?

There are many causes of stomach flu (gastroenteritis), including bacteria such as E coli, Shigella and Salmonella. Viruses can also cause stomach flu and are responsible for 30% to 40% of gastroenteritis cases in children. Common stomach flu viruses include norovirus or Norwalk virus, adenovirus, rotavirus, calicivirus and astrovirus. Stomach viruses are notorious for spreading rapidly because of poor hand washing.

While not as common, parasites such as giardia and cryptosporidium can cause severe diarrhoea and dehydration. Water-borne parasites are common in underdeveloped parts of the world that have unsanitary water supplies. It is recommended that travellers drink only bottled water to avoid water-borne parasites - a potential cause of gastroenteritis.

A lack of good hygiene can result in gastroenteritis. For instance improper hand washing after going to the toilet or after changing a baby's nappy can spread the infectious bug from person to person. Many doctors call stomach flu "a family affair" because it is so highly contagious and usually goes through all members of a family.

When should you seek medical advice for gastroenteritis (stomach flu)?

If you experience symptoms of gastroenteritis and are weak and dizzy, you may be dehydrated. If you cannot drink fluids but continue to lose fluids through high temperature, vomiting and diarrhoea, you should seek medical advice. If you are sleepy or unaware, you should definitely be taken to a doctor or to a hospital's accident and emergency department. Other signs that warrant medical treatment include:

  • Blood in the vomit or stool (poo)
  • Dehydration (check for little to no urination, extreme thirst, lack of tears and dry mouth)
  • Temperature higher than 38C (100.4F)
  • Swollen abdomen or abdominal pain
  • Vomiting that lasts more than 48 hours

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on March 31, 2014

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