Gastroenteritis

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Obesity, Sleep & Internal medicine
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Inflammation of the stomach and intestines causing diarrhea, vomiting, and abdominal pain

Gastroenteritis
Synonyms	Stomach flu, stomach bug, infectious diarrhea, acute gastroenteritis, gastro
Pronounce	N/A
Specialty	Gastroenterology, Infectious disease, Pediatrics, Emergency medicine
Symptoms	Diarrhea, vomiting, nausea, abdominal pain, abdominal cramps, fever
Complications	Dehydration, electrolyte imbalance, acute kidney injury, metabolic acidosis, sepsis, hemolytic uremic syndrome
Onset	Hours to several days after exposure, depending on cause
Duration	Usually several days; often less than 2 weeks
Types	N/A
Causes	Viruses, bacteria, parasites, bacterial toxins, contaminated food, contaminated water
Risks	Young children, older adults, immunocompromised persons, travelers, daycare exposure, nursing home exposure, unsafe food or water
Diagnosis	Clinical evaluation; stool testing when severe, bloody, persistent, outbreak-related, or high-risk
Differential diagnosis	Food poisoning, appendicitis, inflammatory bowel disease, irritable bowel syndrome, ischemic colitis, Clostridioides difficile infection
Prevention	Hand washing, safe food handling, safe water, sanitation, isolation during illness, rotavirus vaccine
Treatment	Oral rehydration therapy, continued feeding, IV fluids when severe, targeted antimicrobial therapy when indicated
Medication	Oral rehydration solution, ondansetron, loperamide, antibiotics in selected bacterial infections
Prognosis	Usually good with rehydration; serious in infants, older adults, and immunocompromised people
Frequency	Very common worldwide
Deaths	Mostly due to dehydration and diarrheal disease in young children in low-resource settings

Gastroenteritis is inflammation or irritation of the gastrointestinal tract, especially the stomach and intestines, causing diarrhea, vomiting, nausea, abdominal pain, and sometimes fever. It is commonly called stomach flu, although it is not caused by the influenza virus. Most cases are infectious and are caused by viruses, bacteria, parasites, or toxins in contaminated food or water.Viral gastroenteritis (stomach flu) - Symptoms and causes(link). Mayo Clinic.

The most important treatment is replacement of lost fluid and electrolytes. Most mild cases improve with oral rehydration therapy, rest, and continued feeding. Severe cases may require intravenous fluids, laboratory testing, stool testing, or targeted treatment for specific pathogens.Norovirus - CDC Yellow Book 2026(link). Centers for Disease Control and Prevention / NCBI Bookshelf.

Overview

Gastroenteritis is one of the most common causes of acute illness worldwide. It can affect people of any age, but the risk of severe dehydration is highest in infants, young children, older adults, pregnant people, and people with weakened immune systems.

The illness may be sporadic, occur in family clusters, or appear as outbreaks in schools, daycare centers, cruise ships, restaurants, hospitals, nursing homes, camps, shelters, and other group settings. Norovirus is a leading cause of acute gastroenteritis outbreaks and foodborne illness in the United States.Norovirus(link). Centers for Disease Control and Prevention.

Terminology

The term gastroenteritis is often used broadly for acute vomiting and diarrhea caused by infection or toxins.

• Gastroenteritis - Inflammation or irritation of the stomach and intestines.
• Acute gastroenteritis - Gastroenteritis lasting a short time, usually days to less than two weeks.
• Infectious diarrhea - Diarrhea caused by viruses, bacteria, or parasites.
• Food poisoning - Illness from contaminated food or toxins, often with vomiting or diarrhea.
• Traveler's diarrhea - Diarrhea occurring during or after travel, usually from contaminated food or water.
• Stomach flu - Common informal term for gastroenteritis, but it is not true influenza.
• Viral gastroenteritis - Gastroenteritis caused by viruses such as norovirus or rotavirus.

Signs and symptoms

Symptoms vary depending on the cause, age, hydration status, and immune function.

Common symptoms

• Diarrhea - Loose or watery stools are a major feature of gastroenteritis.
• Vomiting - Forceful emptying of stomach contents, common in viral gastroenteritis.
• Nausea - Feeling of needing to vomit.
• Abdominal pain - Pain or discomfort in the abdomen.
• Abdominal cramps - Cramping pain caused by intestinal irritation or increased bowel activity.
• Fever - May occur with viral, bacterial, or inflammatory causes.
• Malaise - General feeling of illness or weakness.
• Loss of appetite - Reduced desire to eat during illness.
• Myalgia - Muscle aches may occur with viral illness.
• Headache - May accompany dehydration or viral infection.

Symptoms of dehydration

Dehydration is the most important complication of gastroenteritis.

• Thirst - Early sign of fluid loss.
• Dry mouth - Reduced saliva from dehydration.
• Decreased urination - Fewer wet diapers in infants or reduced urine in older children and adults.
• Dark urine - Concentrated urine due to fluid loss.
• Dizziness - May occur with low blood pressure or dehydration.
• Tachycardia - Fast heart rate from volume depletion.
• Hypotension - Low blood pressure in more severe dehydration.
• Lethargy - Unusual sleepiness or low energy.
• Sunken eyes - Sign of dehydration, especially in children.
• Poor skin turgor - Skin remains tented after being pinched.
• No tears - Lack of tears when crying may indicate dehydration in children.

Warning signs

Some symptoms suggest severe illness or another diagnosis.

• Bloody diarrhea - May suggest invasive bacterial infection, inflammatory bowel disease, ischemic colitis, or other serious disease.
• Persistent vomiting - Inability to keep fluids down increases dehydration risk.
• High fever - May suggest invasive infection or systemic illness.
• Severe abdominal pain - May suggest appendicitis, obstruction, ischemia, or other surgical disease.
• Confusion - May indicate severe dehydration, electrolyte disorder, sepsis, or another emergency.
• Neck stiffness - May suggest meningitis or another serious infection.
• Sepsis - Fever, low blood pressure, confusion, or rapid breathing may signal severe infection.
• Oliguria - Very low urine output can indicate severe dehydration or kidney injury.

Causes

Gastroenteritis can be caused by viruses, bacteria, parasites, and toxins.

Viral causes

Viruses are the most common cause of acute gastroenteritis in many settings.

• Norovirus - A highly contagious virus and leading cause of vomiting and diarrhea outbreaks.
• Rotavirus - Important cause of severe diarrhea in infants and young children; reduced by vaccination.
• Adenovirus - Can cause gastroenteritis, especially in children.
• Astrovirus - Can cause diarrhea, especially in children, older adults, and immunocompromised people.
• Sapovirus - A calicivirus that can cause outbreaks similar to norovirus.
• Enterovirus - Some types can cause gastrointestinal symptoms.
• Coronavirus - Some human coronaviruses can cause gastrointestinal symptoms, though respiratory symptoms are often prominent.

Bacterial causes

Bacterial gastroenteritis may be acquired from contaminated food, water, animals, or infected people.

• Salmonella - Often associated with poultry, eggs, reptiles, contaminated produce, or undercooked food.
• Shigella - Highly contagious cause of dysentery and outbreaks in daycare or crowded settings.
• Campylobacter - Often associated with undercooked poultry or unpasteurized milk.
• Escherichia coli - Includes enterotoxigenic, enteroaggregative, enteropathogenic, enteroinvasive, and Shiga toxin-producing strains.
• Shiga toxin-producing Escherichia coli - Can cause bloody diarrhea and hemolytic uremic syndrome.
• Vibrio cholerae - Causes cholera, a severe watery diarrheal illness.
• Vibrio parahaemolyticus - Associated with raw or undercooked seafood.
• Yersinia enterocolitica - Can mimic appendicitis and may be associated with pork products.
• Clostridioides difficile - Causes antibiotic-associated diarrhea and colitis.
• Staphylococcus aureus - Produces toxins that can cause rapid-onset vomiting after contaminated food.
• Bacillus cereus - Causes vomiting or diarrhea syndromes from contaminated foods such as rice.
• Clostridium perfringens - Causes foodborne diarrhea, often linked to improperly held meats or gravies.
• Listeria monocytogenes - May cause gastroenteritis and serious invasive disease in pregnancy, older adults, and immunocompromised persons.

Parasitic causes

Parasitic gastroenteritis is more common with travel, unsafe water, childcare exposure, immunocompromise, or prolonged diarrhea.

• Giardia duodenalis - Also called Giardia lamblia; causes prolonged diarrhea, bloating, and malabsorption.
• Cryptosporidium - Waterborne parasite that can cause severe disease in immunocompromised people.
• Entamoeba histolytica - Causes amebic colitis and dysentery.
• Cyclospora cayetanensis - Causes prolonged watery diarrhea and may be linked to contaminated produce.
• Cystoisospora belli - Causes diarrhea, especially in immunocompromised people.
• Microsporidia - Can cause chronic diarrhea in immunocompromised persons.

Toxins and noninfectious triggers

Not all vomiting and diarrhea are caused by active infection.

• Bacterial toxin - Preformed toxins can cause rapid vomiting and diarrhea.
• Food poisoning - Illness caused by contaminated food, toxins, or pathogens.
• Medication adverse effect - Antibiotics, metformin, magnesium, chemotherapy, and other drugs can cause diarrhea.
• Food intolerance - Lactose intolerance and other intolerances can mimic gastroenteritis.
• Inflammatory bowel disease - Crohn disease or ulcerative colitis may present with diarrhea and abdominal pain.
• Irritable bowel syndrome - Can cause recurrent abdominal pain and altered stools but usually not fever or dehydration.
• Appendicitis - Can initially mimic gastroenteritis.
• Ischemic colitis - Can cause abdominal pain and bloody diarrhea, especially in older adults.
• Radiation enteritis - Gastrointestinal inflammation after radiation therapy.

Transmission

Infectious gastroenteritis spreads through several routes.

• Fecal-oral transmission - Pathogens from stool reach another person's mouth through contaminated hands, food, water, or surfaces.
• Contaminated food - Undercooked meat, raw seafood, unwashed produce, and improperly stored foods can transmit infection.
• Contaminated water - Unsafe drinking water, recreational water, or untreated water can transmit pathogens.
• Person-to-person transmission - Close contact spreads viruses such as norovirus and rotavirus.
• Fomite - Contaminated surfaces can spread norovirus and other pathogens.
• Animal exposure - Reptiles, poultry, livestock, and pets can carry Salmonella, Campylobacter, or other organisms.
• Healthcare-associated infection - C. difficile and norovirus can spread in hospitals and long-term care facilities.

Risk factors

Risk factors for gastroenteritis or severe disease include age, exposure, and immune status.

• Infants - Have higher dehydration risk because of smaller fluid reserves.
• Young children - Have high exposure through daycare and close contact.
• Older adults - Have higher risk of dehydration, complications, and hospitalization.
• Immunocompromised persons - May have prolonged or severe infection.
• Pregnancy - Some foodborne infections can be more serious during pregnancy.
• Daycare exposure - Increases risk of viral and bacterial spread.
• Nursing home exposure - Outbreaks can spread quickly among vulnerable residents.
• Travel - Travel to areas with unsafe food or water increases risk.
• Antibiotic use - Increases risk of Clostridioides difficile infection.
• Proton pump inhibitor use - May increase susceptibility to some enteric infections.
• Unsafe water - Lack of clean water increases diarrheal disease risk.
• Poor sanitation - Increases fecal-oral transmission.
• Food handling problems - Improper cooking, storage, or hygiene increases risk.

Pathophysiology

Gastroenteritis causes fluid loss and intestinal dysfunction through several mechanisms.

• Intestinal inflammation - Inflammation can damage the intestinal lining and impair absorption.
• Secretory diarrhea - Toxins or pathogens stimulate intestinal secretion of water and electrolytes.
• Osmotic diarrhea - Unabsorbed substances draw water into the intestine.
• Invasive diarrhea - Bacteria invade or injure intestinal tissue, sometimes causing blood and mucus.
• Vomiting reflex - Toxins or viral infection can stimulate nausea and vomiting pathways.
• Electrolyte loss - Sodium, potassium, bicarbonate, and water are lost in stool or vomit.
• Dehydration - Net fluid loss can reduce circulating blood volume.
• Metabolic acidosis - Bicarbonate loss in diarrhea can contribute to acidosis.

Diagnosis

Most mild cases are diagnosed clinically and do not require laboratory testing. Testing is more useful when disease is severe, prolonged, bloody, outbreak-related, or occurs in a high-risk person. The Infectious Diseases Society of America recommends stool testing for important bacterial pathogens when diarrhea is accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis.2017 Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea(link). Infectious Diseases Society of America.

Clinical evaluation

• Medical history - Assesses onset, duration, stool frequency, vomiting, fever, blood, travel, foods, medications, sick contacts, and outbreaks.
• Physical examination - Evaluates abdominal tenderness, hydration, vital signs, mental status, and signs of complications.
• Hydration assessment - Determines whether oral or intravenous rehydration is needed.
• Medication review - Identifies antibiotics, laxatives, metformin, chemotherapy, and other diarrhea-causing drugs.
• Exposure history - Reviews travel, daycare, nursing home, animal exposure, unsafe water, and suspicious foods.
• Pregnancy test - Considered in people of reproductive potential when vomiting or abdominal pain could have other causes.

Stool testing

• Stool culture - May identify Salmonella, Shigella, Campylobacter, and other bacterial pathogens.
• Multiplex PCR panel - Detects multiple viral, bacterial, and parasitic pathogens.
• Shiga toxin test - Important when bloody diarrhea or suspected STEC is present.
• Clostridioides difficile testing - Used when risk factors such as recent antibiotics, hospitalization, or healthcare exposure are present.
• Ova and parasite examination - Considered for persistent diarrhea, travel, immunocompromise, or suspected parasitic disease.
• Giardia antigen test - Used when giardiasis is suspected.
• Cryptosporidium test - Used with persistent watery diarrhea or immunocompromise.
• Fecal leukocytes - Older test sometimes used to suggest inflammatory diarrhea, though more specific tests are preferred.
• Fecal calprotectin - May help distinguish inflammatory bowel disease from functional diarrhea in selected cases.

Blood and urine testing

• Basic metabolic panel - Evaluates sodium, potassium, bicarbonate, kidney function, and dehydration severity.
• Complete blood count - May show leukocytosis, anemia, or hemoconcentration.
• Blood culture - Considered if sepsis, enteric fever, or invasive infection is suspected.
• Urinalysis - May help evaluate dehydration or alternative diagnoses.
• Serum lactate - May be used when sepsis or severe hypoperfusion is suspected.

When testing is more likely needed

• Bloody diarrhea - Testing is recommended because invasive pathogens or STEC may be present.
• Severe dehydration - Laboratory tests may guide fluid and electrolyte replacement.
• High fever - Suggests invasive or systemic infection.
• Sepsis - Requires urgent evaluation and treatment.
• Persistent diarrhea - Diarrhea lasting more than 7 to 14 days may need pathogen testing.
• Immunocompromised host - Broader testing may be needed.
• Outbreak - Testing helps public health investigation.
• Recent antibiotic use - Raises concern for Clostridioides difficile.
• International travel - Raises concern for traveler's diarrhea or parasites.

Differential diagnosis

The differential diagnosis depends on age, symptoms, and severity.

• Food poisoning - Acute vomiting or diarrhea from contaminated food or toxins.
• Inflammatory bowel disease - Chronic or recurrent intestinal inflammation, often with blood, weight loss, or persistent symptoms.
• Irritable bowel syndrome - Functional bowel disorder with recurrent abdominal pain and altered stools.
• Appendicitis - Surgical emergency that may begin with nausea, vomiting, and abdominal pain.
• Bowel obstruction - Can cause vomiting, distension, and abdominal pain.
• Ischemic colitis - Reduced blood flow to the colon, often causing pain and bloody diarrhea.
• Diverticulitis - Inflammation of diverticula causing abdominal pain and fever.
• Pancreatitis - Inflammation of the pancreas causing abdominal pain, nausea, and vomiting.
• Celiac disease - Immune-mediated reaction to gluten causing chronic diarrhea or malabsorption.
• Lactose intolerance - Causes bloating, gas, and diarrhea after lactose intake.
• Medication-induced diarrhea - Diarrhea caused by medicines or supplements.
• Diabetic ketoacidosis - May cause nausea, vomiting, abdominal pain, and dehydration.
• Sepsis - Systemic infection that may present with gastrointestinal symptoms.
• Pregnancy - Nausea and vomiting of pregnancy may mimic gastrointestinal infection.

Treatment

Treatment depends on severity, age, cause, and risk factors.

Rehydration

Rehydration is the central treatment.

• Oral rehydration therapy - First-line treatment for mild to moderate dehydration.
• Oral rehydration solution - Contains the proper balance of salts and glucose for absorption.
• Intravenous fluids - Used for severe dehydration, shock, altered mental status, or inability to keep fluids down.
• Electrolyte replacement - Corrects sodium, potassium, bicarbonate, and other losses when needed.
• Continued feeding - Age-appropriate feeding should continue as tolerated.
• Breastfeeding - Should usually continue during infant gastroenteritis.
• Zinc supplementation - Recommended in some low-resource settings for children with diarrhea.

Diet

• Bland diet - Simple foods may be easier to tolerate during recovery.
• BRAT diet - Bananas, rice, applesauce, and toast may be tolerated, but it is not nutritionally complete.
• Oral fluids - Frequent small sips are useful after vomiting.
• Lactose reduction - Temporary reduction may help some children or adults after viral gastroenteritis.
• Alcohol avoidance - Alcohol can worsen dehydration and gastrointestinal irritation.
• Caffeine avoidance - Caffeine may worsen fluid loss in some patients.
• High-fat food avoidance - Greasy foods may worsen nausea or diarrhea during recovery.

Medications

• Ondansetron - May reduce vomiting and help oral rehydration in selected patients.
• Loperamide - May reduce diarrhea in selected adults without fever, bloody diarrhea, or suspected invasive infection.
• Bismuth subsalicylate - May reduce symptoms in some adults and travelers.
• Acetaminophen - May be used for fever or discomfort when appropriate.
• Antibiotics - Used only for selected bacterial infections or high-risk situations.
• Antiparasitic drugs - Used for confirmed or strongly suspected parasitic infections such as giardiasis or amebiasis.
• Probiotics - May modestly reduce duration in some cases, but benefits vary by strain and patient group.

Antibiotics and antimicrobial therapy

Antibiotics are not useful for viral gastroenteritis and may be harmful in some infections.

• Traveler's diarrhea - May be treated with antibiotics in moderate to severe cases depending on destination and symptoms.
• Shigellosis - Often treated with antibiotics when confirmed or strongly suspected.
• Campylobacter infection - Antibiotics may be used in severe disease or high-risk patients.
• Cholera - Requires aggressive rehydration and may benefit from antibiotics in severe cases.
• Giardiasis - Treated with antiparasitic medication.
• Amebiasis - Requires tissue-active and luminal anti-amebic therapy.
• Clostridioides difficile infection - Requires specific therapy such as vancomycin or fidaxomicin according to current guidelines.
• Shiga toxin-producing Escherichia coli - Antibiotics are usually avoided because they may increase risk of hemolytic uremic syndrome.

Hospital care

Hospitalization may be needed for severe or complicated disease.

• Severe dehydration - Requires intravenous fluids and monitoring.
• Shock - Emergency treatment is needed.
• Acute kidney injury - May occur after severe fluid loss.
• Electrolyte imbalance - Severe sodium, potassium, or acid-base disorders may require monitoring.
• Hemolytic uremic syndrome - Requires urgent evaluation, especially after bloody diarrhea.
• Sepsis - Requires emergency treatment with fluids, cultures, and antimicrobials when indicated.
• Immunocompromised status - May require broader evaluation and treatment.
• Infant illness - Young infants may need closer monitoring.

Prevention

Prevention focuses on hygiene, vaccination, safe food, safe water, and outbreak control.

Hand hygiene

• Hand washing - Washing with soap and water is especially important after using the bathroom, changing diapers, and before preparing food.
• Alcohol-based hand sanitizer - Helpful for many germs but less reliable than soap and water for norovirus.
• Environmental disinfection - Bleach-based or approved disinfectants may be needed for norovirus-contaminated surfaces.
• Diaper hygiene - Proper disposal and handwashing reduce spread in childcare settings.

Food safety

• Food safety - Proper cooking, cooling, storage, and handling reduce foodborne gastroenteritis.
• Cooking temperature - Meat, poultry, seafood, and eggs should be cooked to safe temperatures.
• Cross-contamination - Raw meat and ready-to-eat foods should be kept separate.
• Refrigeration - Perishable foods should be refrigerated promptly.
• Pasteurization - Avoiding unpasteurized milk and juice reduces risk.
• Raw seafood - Raw oysters and shellfish can transmit norovirus or Vibrio species.
• Produce washing - Fruits and vegetables should be washed before eating.

Water and sanitation

• Safe drinking water - Prevents waterborne diarrheal disease.
• Sanitation - Proper sewage disposal reduces fecal-oral spread.
• Water treatment - Boiling, filtration, chlorination, or other methods may be needed when water is unsafe.
• Recreational water illness - Avoid swallowing pool, lake, or splash-pad water.
• Travel medicine - Travelers should follow food and water precautions in high-risk areas.

Vaccination

• Rotavirus vaccine - Recommended for infants in many countries and reduces severe rotavirus gastroenteritis.
• Vaccine schedule - In the United States, infants receive 2 or 3 oral doses depending on vaccine brand.Rotavirus Vaccination(link). Centers for Disease Control and Prevention.
• Herd immunity - Rotavirus vaccination can reduce spread and severe disease in the community.
• Cholera vaccine - Used in selected travel or outbreak settings, depending on country recommendations and availability.
• Typhoid vaccine - Considered for some travelers to areas with risk of enteric fever.

Outbreak control

• Isolation - Sick people should avoid preparing food for others during illness and for a period after symptoms improve.
• School exclusion - Children with vomiting or diarrhea may need to stay home according to local rules.
• Healthcare infection control - Contact precautions may be needed in hospitals and nursing homes.
• Public health reporting - Outbreaks and certain pathogens may require reporting to public health authorities.
• Food handler restriction - Food workers with vomiting or diarrhea should follow local public health guidance before returning to work.

Complications

Complications are more likely in infants, older adults, pregnant people, and immunocompromised people.

• Dehydration - Most common serious complication.
• Electrolyte imbalance - Abnormal sodium, potassium, or bicarbonate levels.
• Acute kidney injury - Can occur from severe dehydration.
• Metabolic acidosis - Can result from bicarbonate loss in stool.
• Hemolytic uremic syndrome - Severe complication of Shiga toxin-producing E. coli infection.
• Reactive arthritis - Can follow infections such as Salmonella, Shigella, Campylobacter, or Yersinia.
• Guillain-Barré syndrome - Rare complication associated with Campylobacter infection.
• Post-infectious irritable bowel syndrome - Persistent bowel symptoms after an infection.
• Malnutrition - May occur with repeated or prolonged diarrheal illness.
• Sepsis - Severe invasive infection can occur in high-risk patients.
• Death - Usually due to dehydration or severe infection, especially in vulnerable populations.

Special populations

Children

Children are at higher risk for dehydration. Oral rehydration solution is preferred over plain water or sugary drinks when dehydration is present.

• Infants - Need prompt evaluation for poor feeding, fewer wet diapers, lethargy, or persistent vomiting.
• Toddlers - Are exposed through daycare and close contact.
• Rotavirus - Vaccination has reduced severe rotavirus disease in many countries.
• Oral rehydration solution - Preferred for mild to moderate dehydration.
• Breastfeeding - Usually should continue during illness.
• Zinc - Recommended for pediatric diarrheal illness in some global health guidelines.

Older adults

Older adults are at increased risk of severe dehydration and complications.

• Dehydration - May develop quickly, especially with diuretics or poor oral intake.
• Medication review - Diuretics, blood pressure medicines, and kidney-affecting drugs may need review by a clinician.
• Nursing home - Outbreaks of norovirus and C. difficile are important concerns.
• Acute kidney injury - More likely with dehydration or chronic kidney disease.
• Hospitalization - May be needed for severe weakness, confusion, or inability to drink.

Immunocompromised people

• Immunocompromised - May develop prolonged, severe, or unusual infections.
• Cryptosporidiosis - Can be severe in advanced immunosuppression.
• Cytomegalovirus colitis - May mimic gastroenteritis in severely immunocompromised patients.
• Chronic diarrhea - Requires broader evaluation.
• Specialist care - Infectious disease or gastroenterology consultation may be needed.

Pregnancy

• Pregnancy - Dehydration, fever, and certain foodborne infections can pose maternal or fetal risks.
• Listeriosis - Important foodborne infection in pregnancy.
• Hydration - Prompt hydration is important.
• Obstetric evaluation - Needed if there are contractions, decreased fetal movement, high fever, or severe dehydration.

When to seek medical care

Medical care is recommended for severe symptoms, dehydration, high-risk patients, or warning signs.

• Dehydration - Very little urine, dizziness, dry mouth, sunken eyes, or lethargy should be evaluated.
• Bloody diarrhea - Blood in stool requires medical assessment.
• Persistent vomiting - Inability to keep fluids down increases dehydration risk.
• High fever - Fever with severe diarrhea may suggest invasive infection.
• Severe abdominal pain - May indicate appendicitis, obstruction, ischemia, or another emergency.
• Confusion - Can indicate severe dehydration, electrolyte imbalance, or sepsis.
• Infant diarrhea - Young infants should be evaluated promptly.
• Older adult diarrhea - Older adults with weakness or dehydration need care.
• Immunocompromised status - Lower threshold for evaluation is appropriate.
• Pregnancy - Pregnant patients should seek care for severe symptoms, dehydration, or fever.
• Persistent diarrhea - Diarrhea lasting more than several days or more than 1 to 2 weeks should be evaluated.
• Recent antibiotic use - Raises concern for Clostridioides difficile infection.
• Travel-associated diarrhea - Severe or persistent diarrhea after travel should be assessed.

Prognosis

Most cases resolve without long-term problems. Viral gastroenteritis often improves within a few days, while some bacterial or parasitic infections may last longer or need specific therapy. The prognosis is best when dehydration is recognized early and treated with appropriate rehydration.

Globally, diarrheal disease remains an important cause of childhood illness and death, especially where clean water, sanitation, oral rehydration therapy, and healthcare access are limited. The World Health Organization reports hundreds of thousands of diarrheal deaths each year among children under age five.Diarrhoeal disease(link). World Health Organization.

Epidemiology

Gastroenteritis is common worldwide. The burden is greatest in young children and in communities with limited access to clean water, sanitation, vaccination, and healthcare. Viral gastroenteritis is common in both high-income and low-income settings, while bacterial and parasitic causes are more closely associated with sanitation, food safety, travel, and water quality.

• Norovirus - Leading cause of acute gastroenteritis outbreaks and foodborne illness in the United States.
• Rotavirus - Historically a major cause of severe childhood diarrhea; vaccination has reduced severe disease.
• Diarrhoeal disease - Remains a major global child-health problem.
• Foodborne disease - A major source of bacterial and viral gastroenteritis.
• Waterborne disease - Important in areas with unsafe water and inadequate sanitation.
• Traveler's diarrhea - Common among travelers to regions with different sanitation or food safety conditions.

History

Acute diarrheal illness has been recognized throughout human history. Major advances in prevention and treatment include safe water systems, sanitation, food safety regulation, oral rehydration therapy, rotavirus vaccination, and modern microbiologic testing.

• Oral rehydration therapy - One of the most important public-health advances for preventing death from diarrheal dehydration.
• Sanitation - Reduced transmission of many diarrheal diseases.
• Rotavirus vaccine - Reduced severe rotavirus gastroenteritis in vaccinated populations.
• Molecular diagnostics - Modern stool PCR panels can rapidly identify multiple pathogens.
• Public health surveillance - Helps identify outbreaks and contaminated food or water sources.

Patient education

Patients and caregivers should focus on hydration, warning signs, hygiene, and preventing spread.

• Oral rehydration solution - Best fluid for dehydration from vomiting or diarrhea.
• Small frequent sips - Helpful when nausea or vomiting makes drinking difficult.
• Hand washing - Prevents spread to family members and caregivers.
• Surface disinfection - Important after vomiting or diarrhea, especially with suspected norovirus.
• Food handling - Sick people should avoid preparing food for others.
• Rest - Helps recovery during acute illness.
• Continued feeding - Normal diet can usually be resumed as tolerated.
• Medical care - Needed for dehydration, blood in stool, severe pain, persistent fever, or high-risk patients.
• Rotavirus vaccine - Helps protect infants from severe rotavirus diarrhea.
• Travel precautions - Safe food and water practices reduce travel-associated diarrhea.

See also

• Diarrhea
• Vomiting
• Dehydration
• Oral rehydration therapy
• Norovirus
• Rotavirus
• Food poisoning
• Traveler's diarrhea
• Cholera
• Clostridioides difficile infection
• Hemolytic uremic syndrome
• Infectious disease
• Gastroenterology
• Pediatrics
• Foodborne illness
• Waterborne disease
• Inflammatory bowel disease
• Irritable bowel syndrome

External links

• CDC - Norovirus
• CDC - Rotavirus
• CDC - Rotavirus vaccination
• WHO - Diarrhoeal disease
• IDSA - Infectious diarrhea guideline
• USDA - Food safety basics
• CDC Travelers' Health - Food and water safety

• Norovirus - CDC Yellow Book, 2026 edition - NCBI Bookshelf