Diet and Nutrition

All You Need to Know About Stomach Flu

All You Need to Know About Stomach Flu

Stomach flu, commonly known as viral gastroenteritis is an infection of the intestines characterized by stomach cramps, nausea and vomiting, watery diarrhea and even fever. People usually get stomach flu through direct contact with an infected person, as well as by drinking contaminated water or by eating contaminated food, prepared or handled by an infected person.

Causes of Stomach Flu

Different types of viruses can lead to a gastrointestinal infection, but most cases of viral gastroenteritis are generally caused by the following two viruses:

  • Norovirus – is one of the leading causes of viral gastroenteritis worldwide, affecting both children and adults. Anyone can get infected with Norovirus. This type of virus tends to easily spread from one person to the other by direct contact, or even by drinking contaminated water or by sharing the same food and the same eating utensils. Norovirus can spread easily in schools, day cares, nursing homes, hospitals, dormitories, cruise ships, etc.In the United States, norovirus infections mostly occur from November until April each year. An infection with one type of Norovirus does not protect you from other types of norovirus, meaning that you can get infected a couple of times within a year. 
  • Rotavirus is most common among babies and children. They usually get infected by putting their fingers into the mouth after they have touched objects contaminated with the virus. In adults, even though there might be no signs and symptoms at all, a person can be contagious and spread the virus into the community. Children are more likely to get a gastrointestinal infection with rotavirus from December until June each year.

Symptoms of Stomach Flu 

Stomach flu affects the gastrointestinal system in humans.


Characteristic symptoms of stomach flu are:

In mild to moderate cases of stomach flu, these signs and symptoms resolve within 3 days, usually lasting a day or two. However, in certain cases, the signs and symptoms of stomach flu may last up to 10 days.

In babies and children, pregnant women, elderly people, as well as in adults with chronic medical conditions, stomach flu tends to be more severe than in young and healthy adults. For this reason, the above mentioned categories should pay more attention to the signs and symptoms of stomach flu.

In certain cases medical attention is required, especially when:

  • You have been vomiting for more than 2 days
  • You have watery stools many times during a day, for more than 2 days
  • You are dehydrated
  • You are vomiting blood
  • You noticed blood in your bowel movements
  • You have a fever higher than 40 degrees Celsius, etc.

Remedies for Stomach Flu 

No specific treatment for stomach flu exists as it is a viral infection. Preventing stomach flu from occurring in the first place is the best treatment possible. However, once stomach flu symptoms become noticeable, there are a few things every person can do at home for faster recovery like:

  • Let your stomach take its time and avoid eating any solid foods for a couple of hours.
  • Drink water constantly in small sips throughout the day to prevent diarrhea. You should avoid any beverages that will make your diarrhea and vomiting get worse, such as juices.
  • Once you start to feel better and the vomiting or diarrhea has stopped, start eating light food such as rice, toast or even crackers. If you start feeling sick again, stop eating.
  • Avoid certain types of food such as foods high in fat, spicy foods, alcohol, caffeine, sugary foods, etc., until you have fully recovered as they will just worsen your symptoms.

In general, the stomach flu resolves within 24 to 48 hours even without any medication. However, the above mentioned measures can help speed up the recovery time. People suffering from stomach flu should be cautious when considering over-the-counter medications as sometimes they can make the situation get worse. Anti–diarrheal medications are dangerous, especially for young children, as they can make the infection last even longer. There is no need for antibiotics as stomach flu is a viral infection.

In certain cases, water is not enough as a lot of body fluids are lost through vomiting and diarrhea. Beverages that replace the necessary minerals and salt are known as oral rehydration solutions. You can find these oral rehydration solutions in every drug store nearby or in every pharmacy. You won’t need a prescription for them.

When it comes to stomach flu, dehydration is perhaps the biggest concern. In severe cases of stomach flu with constant diarrhea and vomiting over a couple of days, intravenous fluids and electrolytes are recommended in order to substitute the body fluids and electrolytes lost through diarrhea and vomiting, in order to prevent dehydration.

If you notice any signs or symptoms of dehydration, you should seek immediate medical help.

Possible signs and symptoms of dehydration due to stomach flu are:

  • A dry mouth and dry throat
  • Dizziness, especially when standing
  • Low blood pressure
  • Excessive thirst
  • Dark urine as well as decreased urine output, etc.

Prevention of Stomach Flu

The best treatment option for stomach flu is to prevent it from occurring in the first place.

These preventive measures can help reduce the risk of getting viral gastroenteritis:

  • Maintain good hygiene – Use water and soap to wash your hands properly, especially after using the toilet or before having a meal or cooking it.
  • Prepare the food well – Wash all the fruits and vegetables carefully. Also, cook the food thoroughly before eating it.
  • Avoid contact with an infected person as much as possible.
  • Wash your laundry carefully as the virus can be transmitted from one person to the other through contaminated clothing with vomit or stool.
  • Clean and disinfect carefully any surfaces that have been contaminated, especially after vomiting or diarrhea.
  • Don’t prepare food for other family members as long as you are sick, and even for a couple of days after your symptoms subside.

In certain countries, including the United States, there is a vaccine against certain stomach viruses. This vaccine against Rotavirus is effective when it comes to preventing severe viral gastroenteritis.

In the United States, the two rotavirus vaccines commonly administered are RotaTeq (RV5) and Rotarix (RV1). RotaTeq vaccine is administered in three doses at ages of 2 months, 4 months and 6 months, white the Rotarix vaccine is administered in two doses at ages of 2 months and 4 months. Both vaccines are oral vaccines gives by mouth. A child should finish all the doses of rotavirus vaccines before the age of 8 months old for a better effect. On the other hand, there is no vaccine for norovirus gastrointestinal infections.

Difference between Stomach Flu and Food poisoning

Stomach flu is often misdiagnosed as food poisoning or vice versa due to their similar signs and symptoms. Stomach flu is a gastrointestinal infection with a certain virus, while food poisoning is caused by eating contaminated food with bacteria, viruses, or parasites.

The symptoms of stomach flu can take up to three days after contamination to develop. In cases of food poisoning, nausea and vomiting, as well as, diarrhea start usually within the first 2 to 6 hours after eating the contaminated food. In general, the person will feel better within a day in case of a food poisoning, even though sometimes it may take a few hours and up to several days. In cases of stomach flu, the signs and symptoms usually last for about three days, sometimes even for 10 days or longer.

Stomach flu is contagious and can easily spread from one person to the other. Stomach flu outbreaks due to notavirus or rotavirus are common in schools, day cares, dormitories, etc. On the other hand, food poisoning is not contagious and it can’t spread from one person to the other. However, it is possible for a couple of people to get food poisoning if they all had the same food. Also, certain forms of food poisoning are spread via the fecal–oral route. 

Food poisoning is also more common compared to stomach flu affecting about 1 in 6 Americans each year. The most common causes of food poisoning are Escherichia coli and Staphylococcus.

Certain types of food increase your risk of getting a food poisoning.

The following foods commonly lead to food poisoning:

  • Raw meat
  • Undercooked and raw eggs
  • Unpasteurized milk
  • Unpasteurized and soft cheeses such as feta or brie
  • Raw fish
  • Oysters
  • Undercooked rice
  • Unwashed fruits and vegetables
  • Contaminated water

A certain type of food poisoning known as botulism can be fatal. Botulism is caused by bacteria known as Clostridium botulinum and if not diagnosed and treated on time, it can lead to death. Luckily, botulism is extremely rare in the United States. The bacteria itself produces a toxin which affects the nervous system causing slurred speech, blurred vision, drooping eyelids, etc.

When it comes to diagnosis, no specific tests are necessary in cases of stomach flu. Diagnosis is basically suggested by the signs and symptoms described by the patient. In cases of food poisoning, the diagnosis is also mostly made through anamnesis and patient examination. However, in food poisoning, stool cultures can identify the type of bacteria, parasite, fungi or virus that caused the food poisoning.

The outlook of stomach flu is generally good and in general, patients fully recover within a couple of days without any complications and without any specific medications. The outlook of food poisoning is also good and patients fully recover as well within a couple of days without any long–term complications. However, in severe cases of both stomach flu and especially food poisoning, professional medical care is necessary.

A person should seek medical help especially when there is a presence of blood in the stool, if there is blood in vomiting, if high fever develops or if a person has severe abdominal pain and cramps, as in these cases, some serious bacteria or viruses may cause the signs and symptoms, meaning that proper medical diagnosis and treatment is required.

How long is stomach flu contagious?

A person who shows the symptoms of stomach flu is contagious starting from that very moment and perhaps even a little bit before the symptoms become noticeable. It all depends on which virus is causing the stomach flu, as the contagious period is slightly different for different stomach viruses.

In a gastrointestinal infection with Norovirus, a person is contagious even 3 days after the symptoms have resolved completely. However, the signs and symptoms of Norovirus infection become noticeable only 24–72 hours after contamination, sometimes even longer, meaning that a person is contagious even before the signs and symptoms become noticeable. Also, sometimes it is possible for a person to be contagious even a few weeks after the symptoms of the gastrointestinal infection resolved.

In a gastrointestinal infection with Rotavirus, a person is contagious for about 2 weeks, sometimes even more. A person starts to show the symptoms of stomach flu usually one to three days after exposure to the virus.

As mentioned, the period in which a person is contagious and can spread the virus to other people varies from a few days to a few weeks, always depending on which virus is causing the stomach flu. However, by washing hands regularly especially after using the toilet, by avoiding direct contact with an infected person, and by not sharing the same food and eating utensils with others, stomach flu can be prevented effectively.

Key Takeaways

  • Stomach Flu is a gastrointestinal infection caused mostly by two types of viruses, Norovirus and Rotavirus.
  • Stomach Flu and food poisoning have similar signs and symptoms even though they don't have the same cause. 
  • There is no specific treatment for stomach flu and it usually resolves within 24 to 48 hours.