Gastroenteritis is inflammation of the stomach and intestines, often due to an infection. It causes symptoms such as abdominal pain, vomiting, and diarrhea. Treatment typically focuses on managing symptoms.

Gastroenteritis, which people commonly call stomach flu, can affect both adults and children. It has many possible causes, such as viruses and bacteria.

This article discusses the symptoms and causes of gastroenteritis in more detail. It also looks at diagnosis, treatment options, when to contact a doctor, and more.

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Symptoms of gastroenteritis in adults may include:

  • loss of appetite
  • nausea
  • vomiting
  • abdominal pain
  • watery diarrhea
  • a general feeling of discomfort (malaise)
  • fatigue
  • muscle pain (myalgia)

The character and severity of gastroenteritis symptoms depend on the cause of the condition. Generally, viral gastroenteritis occurs suddenly and lasts 1–3 days in otherwise healthy adults.

Learn more about the symptoms of acute gastroenteritis.

Possible causes of gastroenteritis include:

In the United States, viruses are the most common cause, and most cases are due to norovirus or rotavirus. Astrovirus and adenovirus may also cause gastroenteritis.

A person typically contracts gastroenteritis after person-to-person contact or after consuming food or drink that carries a pathogen that can cause the condition.

Less commonly, gastroenteritis may occur after a person ingests medication or certain chemical toxins, such as plant substances or metals.

For generally healthy adults, gastroenteritis is typically not a serious condition. However, it can cause severe symptoms and dehydration.

It is important for a person who is at high risk of severe symptoms to contact a doctor for advice if they suspect gastroenteritis. High risk groups can include:

  • pregnant people
  • older adults
  • people with compromised immune systems
  • people with serious health conditions

The following serious symptoms may indicate severe viral gastroenteritis or a more serious health problem — if a person experiences any of these, they should contact a doctor:

  • lack of energy
  • irritability or other changes in mental state
  • diarrhea for more than 2 days
  • high fever
  • frequent vomiting
  • passage of six or more loose stools in a day
  • severe pain in the rectum or abdomen
  • black and tarry stool
  • stool that contains pus or blood
  • dehydration

Learn about the symptoms of dehydration.

To reach an accurate diagnosis, a doctor will usually begin by taking a full medical history, asking questions about symptoms, and performing a physical examination.

The doctor may also request a stool test and possibly imaging tests such as a CT scan to rule out other gastrointestinal disorders that can cause similar symptoms.

In many cases, gastroenteritis resolves without treatment. Treatment typically focuses on managing symptoms, maintaining hydration, and countering fluid and electrolyte loss.

Medications that may help manage the symptoms include:

A doctor may recommend hospital admission for people with severe dehydration or uncontrollable vomiting.

Home remedies such as the following may help people manage gastroenteritis symptoms:

  • staying at home and getting plenty of rest
  • staying hydrated
  • consuming nutrient-rich foods in small amounts
  • avoiding fatty, sugary, very high fiber, or spicy foods
  • taking probiotic supplements
  • avoiding use of nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen

Learn about foods to eat with gastroenteritis.

Dehydration is a common complication of gastroenteritis. This may cause the following symptoms in adults:

  • dry mouth
  • extreme thirst
  • tiredness
  • dark-colored urine
  • decreased skin turgor, which means the skin does not quickly return to its usual appearance after a person pinches and releases it
  • sunken eyes or cheeks
  • fainting or lightheadedness

People with persistent diarrhea and vomiting may experience fast heart rate (tachycardia) and low blood pressure (hypotension). In severe cases, a person may experience hypovolemic shock.

Gastroenteritis may also have long-term effects. A 2018 study found that gut infection and subsequent gastroenteritis change the gut microbiota. This may lead to a decrease in the quantity and diversity of good bacteria in the gut, which can cause long-term health problems.

It is best for a person to contact a doctor if they have concerns about the possible complications of gastroenteritis.

Microorganisms that cause gastroenteritis spread through contact. The following steps may help people avoid these microorganisms:

  • staying at home when unwell
  • regularly washing hands
  • disinfecting work surfaces

When traveling, it is best for a person to:

  • drink bottled water and other beverages if possible
  • consume local water only after boiling it for 3 minutes
  • eat only well-cooked foods
  • avoid raw foods and vegetables except for those covered in skin that needs peeling
  • avoid street foods

Learn more about preventing gastroenteritis.

Here are some frequently asked questions about gastroenteritis.

How do you get rid of gastroenteritis in adults?

Gastroenteritis may go away on its own without medical treatment. However, medications such as antidiarrheal drugs can help relieve symptoms.

What are the stages of gastroenteritis?

The stages of gastroenteritis may depend on the cause. In viral gastroenteritis, which most commonly results from norovirus, a person begins experiencing symptoms 12–48 hours after contact with the virus (this is the incubation period).

A person is likely to recover within 1–3 days. If symptoms last longer than this, it is best for a person to contact a doctor.

What can be mistaken for gastroenteritis?

Other conditions that can have similar symptoms to gastroenteritis include:

  • irritable bowel syndrome
  • acute appendicitis
  • diverticulitis
  • inflammatory bowel disease
  • bowel obstruction
  • cholecystitis
  • viral upper respiratory illnesses such as the flu
  • certain types of bacterial pneumonia

A doctor can order tests to confirm the diagnosis and rule out other possible causes.

Gastroenteritis can affect both children and adults. It may occur as a result of viruses, bacteria, parasites, or certain chemicals. Symptoms typically include diarrhea, vomiting, and abdominal pain.

Adults may be able to manage gastroenteritis at home by getting plenty of rest, drinking enough fluids, and avoiding certain types of food.

People who have a higher risk of complications or are experiencing severe or persistent symptoms should seek medical advice.