How Long Does the Stomach Flu Last?

Stomach flu is not a flu, but it is a virus.

Stomach flu or viral gastroenteritis is an infection caused by a virus that infects your stomach. Although the term has flu in it, it is not a true flu. You may experience the following symptoms

• Watery diarrhea
• Abdominal cramps/pain
• Nausea
• Vomiting
• Occasional muscle pain
• Headache
• Sometimes low-grade fever
• Weakness

If you come in contact with an infected person, ingest contaminated food or water or share your personal items such as plates and toothbrushes, you are likely to contract a stomach virus.

If you are otherwise healthy, you will probably recover without complications.

Although it is often called stomach flu, it is not caused by influenza viruses. Stomach flu (viral gastroenteritis) is caused by various viruses including

• Noroviruses: This is the most common cause of foodborne illness in both children and adults worldwide. It can spread through families and communities. It is likely to spread among people who live in confined spaces. Mostly, you pick up the virus from contaminated food or water, although person-to-person transmission is also possible.
• Rotaviruses: This  is the most common cause of viral gastroenteritis in children and babies who put their fingers and other contaminated objects in their mouths. The infection is most severe in newborn babies and children. Adults infected with rotavirus may not show any symptoms; however, they still can spread the infection.

Some shellfish, especially raw or undercooked oysters, may also make you sick. In many cases, the virus is passed through the fecal-oral route.

• Symptoms that include vomiting and diarrhea, fever and stomach pain can last for one to three days depending on the cause.
• Diarrhea may persist longer, for up to 10 days, after the disappearance of other symptoms.
• Even if you are feeling better and even if your symptoms subside, you can be still contagious from a few days up to two weeks or more, depending on which virus caused your stomach flu.
• Because the symptoms are similar, viral diarrhea can be easily confused with diarrhea caused by other bacteria (bacteria that cause cholera or diarrheal illnesses).
• Your infection may range from mild to severe. If you are healthy and drink enough fluids to replace fluids lost from vomiting and diarrhea, then it will not cause any problems in recovery. However, if you have complications such as dehydration (severe loss of water and essential salts and minerals), it may require more attention.
• Babies, veterans and people with a low immune system (human immunodeficiency virus [HIV], cancer, or other severe illnesses) may become severely dehydrated when they lose more fluids than they can replace. Sometimes, hospitalization may be required to replace the lost fluids through intravenous fluid supply. Dehydration can be fatal, but it is rare.

Worldwide, people of every age, race and background are affected by stomach flu (gastroenteritis); however, the following people are more susceptible to it

• Newborn babies and children, especially in childcare centers and elementary schools, are more vulnerable to catch these infections.
• Older adults tend to catch the infection due to a weakened immune system.This applies especially to veterans in nursing homes who are more vulnerable and they can pass the infection on to other close contacts.
• Anywhere where groups of people come together in close quarters can be an environment for transmission of intestinal infection.
• People with a weakened immune system because of diseases such as human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and cancer or due to chemotherapy are at risk of infection.
• In the northern hemisphere, rotavirus and norovirus are most active between October and April.

Your doctor will likely diagnose gastroenteritis based on

• Your symptoms
• A physical examination
• The presence of similar cases in your community
• A rapid stool test to detect rotavirus or norovirus or to rule out other possible bacterial or parasitic infections

Your pediatrician may assess your child for the degree of dehydration by checking 

• Blood pressure, pulse, heart rate
• Skin turgor
• Fontanelle (soft part) on the frontal head
• Mucous membranes such as the tongue and eyes for tears
• Mental status (consciousness, cry and response)
• Urine output and thirst