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Overview

What Is Infectious Gastroenteritis?

Infectious gastroenteritis is an infection that causes inflammation in the stomach or intestines. It often leads to sudden digestive symptoms such as diarrhea, nausea, vomiting, and abdominal cramps. Viruses, bacteria, and parasites can cause gastroenteritis, and anyone can develop it. Acute gastroenteritis usually begins quickly and may spread through contaminated food, water, hands, or surfaces.

Symptoms

Infectious Gastroenteritis Symptoms

  • Watery diarrhea.
  • Nausea.
  • Vomiting.
  • Abdominal cramps.
  • Abdominal pain.
  • Fever.
  • Headache.
  • Muscle aches.
  • Signs of dehydration, such as very dark urine, dry mouth, dizziness, or reduced urination.
  • Blood in the stool or vomit.

WHEN SYMPTOMS NEED ATTENTION

Know when to seek urgent help

Symptoms and severity can vary depending on the pathogen, a person’s age, and their overall health. Seek urgent medical assessment for severe dehydration, confusion, persistent vomiting, bloody stool, or severe abdominal pain.

How It Spreads

How Infectious Gastroenteritis Spreads

Infectious organisms in stool or vomit can reach another person’s mouth through contaminated hands, surfaces, food, or water. This fecal–oral spread can happen through person-to-person contact, shared household areas, unsafe food or water, and exposure during travel. Viral gastroenteritis viruses are especially easily spread in close-contact settings.

  • Touching contaminated surfaces and then touching the mouth can transfer infectious organisms.
  • Eating food prepared by someone who is infected or has not washed their hands properly can cause infection.
  • Drinking contaminated water or eating contaminated food can transmit the infection.
  • Having close contact with a person who is vomiting or has diarrhea can lead to exposure.
  • Infectious particles released during vomiting or left in contaminated bathroom areas can spread illness.

Risk Factors

Risk Factors for Infectious Gastroenteritis

  • Close contact with someone who has vomiting or diarrhea increases exposure risk.
  • Poor hand hygiene or touching shared contaminated surfaces can allow infection to spread.
  • Eating undercooked, contaminated, or improperly stored food can cause illness.
  • Drinking untreated or contaminated water increases the risk of infection.
  • Recent travel to an area with limited sanitation can increase exposure to unfamiliar pathogens.
  • Infants, older adults, pregnant people, and immunocompromised people may experience more severe illness.
  • A chronic condition that increases the risk of dehydration or infection can make gastroenteritis more dangerous.
  • Recent antibiotic use can increase the risk of certain diarrheal infections.

Complications

Complications of Infectious Gastroenteritis

  • Dehydration can develop when diarrhea and vomiting cause loss of fluids and electrolytes.
  • Electrolyte disturbances can affect muscles, nerves, or the heart.
  • Acute kidney injury can result from severe fluid loss.
  • Seizures or altered consciousness may occur in severe cases of dehydration or electrolyte imbalance.
  • Bloodstream infection or other invasive complications can occur with certain bacterial pathogens.
  • Vomiting, diarrhea, or dehydration can worsen existing medical conditions.

HIGHER-RISK COMPLICATIONS

Some people need earlier advice

Infants, older adults, pregnant people, and people with weakened immune systems may become dehydrated or seriously ill more quickly. Contact a clinician early if symptoms develop in someone in one of these groups.

Diagnosis

How Infectious Gastroenteritis Is Diagnosed

Clinicians review when symptoms began, how long they have lasted, possible exposures, recent travel, food history, medication use, and hydration status. They also perform a general examination and check the abdomen for tenderness or other concerning findings. Many cases can be assessed from the history and examination, but testing may be useful when illness is severe, prolonged, bloody, linked to an outbreak or travel, or occurs in a high-risk person.

When testing may be needed

  • Stool tests may identify bacteria, viruses, parasites, or toxins.
  • Blood tests may assess infection, inflammation, kidney function, and electrolyte levels.
  • Additional imaging or procedures may be considered when severe abdominal pain or another condition is suspected.

Treatment & Management

Infectious Gastroenteritis Treatments and Management

When medicines may help

  • Oral rehydration solution is preferred when vomiting or diarrhea causes meaningful fluid loss.
  • Intravenous fluids may be needed for severe dehydration or an inability to keep fluids down.
  • Antibiotics are reserved for selected bacterial infections and should not be taken without medical guidance; they do not treat viral gastroenteritis.
  • Antiparasitic treatment may be used when a parasite is identified or strongly suspected.
  • Anti-nausea or anti-diarrheal medicines should be used only when appropriate for the person’s age, symptoms, and medical history, with clinician or pharmacist advice when needed.

Prevention

How to Prevent Infectious Gastroenteritis

  • Wash hands with soap and water after using the bathroom, changing diapers, or caring for someone who is ill.
  • Wash hands before preparing or eating food.
  • Cook food thoroughly and refrigerate perishable foods promptly.
  • Use safe drinking water and avoid unpasteurized foods or beverages when advised.
  • Clean and disinfect surfaces contaminated by vomit or diarrhea.
  • Avoid preparing food for others while sick and follow local guidance about returning to school or work.
  • Stay up to date on recommended vaccines that prevent specific causes of gastroenteritis, such as rotavirus in infants.

Outlook and Prognosis

Outlook for Infectious Gastroenteritis

Many acute cases of infectious gastroenteritis improve within several days, but the duration can vary by pathogen, immune status, age, and complications. Hydration status is a major factor in recovery, especially when vomiting or diarrhea is frequent. Some infections last longer or require medical treatment, so improvement should be monitored rather than assumed.

When Should You See a Doctor

When Should You See a Doctor for Gastroenteritis?

SEEK MEDICAL CARE

Get prompt help for severe symptoms

Seek prompt medical evaluation for severe dehydration, inability to keep fluids down, bloody stool or vomit, severe or localized abdominal pain, confusion, fainting, persistent high fever, or symptoms that are not improving.

  • Contact a clinician if diarrhea or vomiting persists longer than expected or repeatedly returns.
  • Contact a clinician after recent travel, suspected food poisoning, antibiotic use, or known exposure to an outbreak.
  • Seek earlier advice for infants, older adults, pregnant people, and people with weakened immune systems or serious chronic conditions.
  • Seek emergency care for collapse, severe confusion, trouble breathing, or signs of shock.

Branches

2 topics

Symptoms

4 topics

  • Infectious Gastroenteritis

    Abdominal Pain

  • Infectious Gastroenteritis

    Diarrhea

  • Infectious Gastroenteritis

    Nausea

  • Infectious Gastroenteritis

    Vomiting