When most people feel sick in their stomach, they look for a cause. Many will wonder whether it is a stomach bug or something they ate that is behind their illness.

Stomach sickness is often passed off as the stomach flu or food poisoning, but since the symptoms are so similar, it is easy to confuse the two.

People need to understand which illness they are suffering from to treat it properly.

What is a stomach virus?

Though nicknamed the stomach flu, there is no connection between a stomach virus and real flu.

A man holds his stomach in discomfort.
The most common cause of stomach flu in the U.S. is norovirus.

Stomach flu is caused by a viral infection that attacks the digestive system while real flu attacks the respiratory system.

Different strains of the stomach virus exist. According to the Centers for Disease Control and Prevention (CDC), the most common cause in the United States is norovirus. It is composed of a group of related viruses.

How is a stomach virus spread?

Stomach viruses are highly contagious and can spread quickly. People infected with a stomach virus are contagious from the moment they begin feeling ill and also for the first few days after they recover.

A stomach virus can be spread in several different ways:

  • Eating food or drinking liquids that have been contaminated with the virus
  • Having direct or indirect mouth contact with an infected person or surface with the virus on it
  • The virus is also found in the vomit and stool of infected people

People who are caring for someone who has the stomach virus should take precautions.

Symptoms of stomach viruses

A stomach virus has a few common symptoms that can last for up to 10 days. They include:

  • Diarrhea that may be watery or bloody
  • A loss of appetite
  • Nausea or vomiting
  • Stomach cramps, muscle aches, or weakness
  • Low-grade fever
  • Headaches
  • Light-headedness or dizziness

Stool is not usually bloody with a stomach virus, but bloody stool could signal a more serious infection.

Diagnosis of stomach virus

There is no single testing method for a stomach virus. A doctor will likely go by a patient’s symptoms when making a diagnosis.

A rapid stool test can be used to detect the rotavirus or norovirus, but there are no quick tests for other viruses. A stool sample can also be used to rule out a possible bacterial or parasitic infection.

Many people simply try to stay in bed, get plenty of rest, stay hydrated, and take over-the-counter drugs until the bug runs its course. Unfortunately, there is no specific medical treatment for a stomach virus, and medical treatment consists of self-care measures.

Treatment and prevention

There are a few things that people can do at home while recovering from a stomach virus:

A woman lies in bed holding her stomach.
People with a stomach virus should avoid food for a while to let their stomachs settle.
  • Let the stomach settle. Try not to eat any solid foods for several hours.
  • Suck on ice chips or take small sips of water. People should drink plenty of liquids to not get dehydrated. Avoid juice or other beverages which can make diarrhea worse.
  • Ease back into eating. Start with bland easy-to-digest food such as soda crackers, toast, and rice. Stop eating if nausea returns.
  • Avoid certain substances until feeling better. These include dairy, caffeine, alcohol, sugar, and fatty or highly seasoned foods.

People should be cautious of over-the-counter medications as some can make the infection worse. Even anti-diarrhea medications can make the situation worse if the cause of the infection is certain bacteria.

The stomach virus typically goes away within 24 to 28 hours, but home care is vital to a speedy recovery.

People should see a doctor if they have a stomach virus and have any of the following symptoms:

  • Bloody stool or vomit
  • Unable to keep liquid down for at least 24 hours
  • Dehydration
  • Fever above 104°F

Tips for preventing a stomach virus

The CDC estimate that norovirus causes 19 to 21 million illnesses, 56,000 to 71,000 hospitalizations, and 570 to 800 deaths each year. These preventive measures can help reduce the risk of catching a stomach virus.

  • Practicing proper hand hygiene. People should always wash their hands with soap and water, especially after using the toilet, changing diapers, or before eating or preparing food.
  • Taking precautions when in the kitchen. It is important to rinse fruits and vegetables and cook all food thoroughly.
  • Cleaning and disinfecting potentially contaminated surfaces. People should immediately clean and disinfect contaminated surfaces after vomiting or diarrhea.
  • Washing laundry thoroughly. The stomach virus can easily be carried from person to person so any clothing contaminated with vomit or stool should be removed and washed.
  • Keeping a distance from anyone who is infected with the virus. If someone in a household is infected, they should use separate personal items such as plates and glasses.

There is a vaccination available in some countries that fights against certain stomach viruses. The vaccine can be effective in helping to prevent severe symptoms of the virus when given to children in the first year of their life.

What is food poisoning?

Food poisoning and the stomach flu are often confused due to their similar symptoms. Food poisoning is caused by eating food that contains bacteria, viruses, or parasites, which can get into food at various points during production.

A woman is about to throw up into a bowl.
The symptoms of food poisoning occur more quickly than those of a stomach virus.

Cross-contamination is often the cause of food poisoning. This is when harmful organisms transfer from one surface to another. Raw foods and ready-to-eat foods such as salads are particularly at risk of contamination.

Bacteria can also grow rapidly when foods such as meats, dairy products, and sauces are not kept at the right temperature. The bacteria and other harmful organisms can produce poisonous substances that cause inflammation of the intestines when eaten.

Contamination can also occur at home if food such as raw meat is not handled or cooked properly.

Salmonella and E. coli are two common types of bacteria linked to food poisoning.

Symptoms of food poisoning

While symptoms of a stomach virus can take days to develop, food poisoning symptoms can occur within 6 hours of eating. People may experience diarrhea, nausea, vomiting, stomach pain and cramps, or a fever. Sickness from food poisoning can last from a few hours to several days, but most cases clear up within a day.

People can usually suspect food poisoning if others who consumed the same food are also ill, or they ate unrefrigerated food. Salads, raw or undercooked poultry, eggs, seafood, and other dairy-based products are high-risk foods for food poisoning.

Diagnosing food poisoning can be difficult, especially if the particular cause cannot be identified. A doctor may be able to do tests on stool to see what germ is causing the illness.

Preventing food poisoning

People can help prevent food poisoning by making sure meats, salads, dressings, and other foods are kept at the right temperature. People should not eat food that has been kept out for more than 2 hours.

It is important for people to wash their hands when handling any raw meat. They should also make sure not to eat raw meat, raw eggs, or sauces made with raw eggs. During picnics or parties, food that should be refrigerated should be kept on ice. People should also be careful when eating out.