Viral Gastroenteritis (Stomach Flu): How It Spreads, and What Actually Helps You Recover
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is viral gastroenteritis (stomach flu) and how is it treated?
Viral gastroenteritis, commonly called stomach flu, is an intestinal infection that causes watery diarrhea, stomach cramps, nausea or vomiting and sometimes a low-grade fever; it is not influenza. Norovirus and rotavirus are the main causes. Antibiotics do not work, so recovery centers on staying hydrated. Dehydration is the main danger, especially for infants and older adults. [1] [2]
What the research says
Hand-washing promotion cuts diarrhoea by about 30%. A Cochrane review of 29 randomized trials found that hand-washing programs reduced diarrhoea episodes by roughly 30%: incidence rate ratio 0.70 (95% CI 0.58–0.85) in child day-care centres and schools in mainly high-income countries (9 trials, 4,664 participants) and 0.71 (95% CI 0.62–0.81) in community trials in low- and middle-income countries (9 trials, 15,950 participants) (Ejemot-Nwadiaro et al., Cochrane Database of Systematic Reviews, 2021) [3].
Rotavirus vaccines sharply lower hospitalization. A meta-analysis of 20 randomized trials and 38 case-control studies in children under 5 found much lower odds of rotavirus gastroenteritis hospitalization in fully vaccinated children — odds ratio 0.347 (95% CI 0.279–0.432) with Rotarix and 0.272 (95% CI 0.197–0.376) with RotaTeq — with no serious adverse event risk reported (Sun et al., JAMA Pediatrics, 2021) [4].
Drinking fluids works about as well as an IV for most children. A Cochrane review of 17 trials (1,811 children) found no clinically important differences between oral and intravenous rehydration: about 1 in 25 children treated orally later needed IV fluids (risk difference 4%, 95% CI 1–7), and hospital stays were shorter with oral rehydration (−1.2 days, 95% CI −2.38 to −0.02) (Hartling et al., Cochrane Database of Systematic Reviews, 2006) [5].
What Is Viral Gastroenteritis?
Viral gastroenteritis is an intestinal infection that includes signs and symptoms such as watery diarrhea, stomach cramps, nausea or vomiting, and sometimes fever [1].
Although it is commonly called stomach flu, gastroenteritis is not the same as influenza. The flu affects only the respiratory system — the nose, throat, and lungs. Gastroenteritis, on the other hand, attacks the intestines [1].
The stomach, small intestine, and large intestine (colon) make up the digestive tract, which processes the food you eat. Viral gastroenteritis is an inflammation of these organs caused by a virus. The most common way to develop it is through contact with an infected person or by consuming contaminated food or water [1].
Symptoms: What the Stomach Bug Feels Like
Depending on the cause, viral gastroenteritis symptoms may appear within 1 to 3 days after you are infected, and they can range from mild to severe [1].
Symptom | What to know |
|---|---|
Watery diarrhea | Usually nonbloody — bloody diarrhea usually means a different, more severe infection |
Nausea and vomiting | Can occur alone or together |
Stomach cramps and pain | Abdominal pain and cramping |
Muscle aches or headache | Occasional |
Low-grade fever | Sometimes present |
Symptoms usually last just a day or two, but occasionally they may last up to 14 days. Because the symptoms are similar, it is easy to confuse viral diarrhea with diarrhea caused by bacteria — such as Clostridioides difficile, salmonella, and Escherichia coli — or parasites, such as giardia [1].
Causes: Norovirus and Rotavirus
You are most likely to get viral gastroenteritis when you eat or drink contaminated food or water. You may also be likely to get it if you share utensils, towels, or food with someone who has one of the viruses that cause the condition [1]. Many viruses can cause gastroenteritis; the two most important are:
Virus | Who it affects | How it spreads |
|---|---|---|
Norovirus | Children and adults; the most common cause of foodborne illness worldwide | Contaminated food or water; close contact with infected people; shared food; touching a contaminated surface and then your mouth |
Rotavirus | The most common cause worldwide in children; most severe in infants and young children | Contaminated fingers or objects put in the mouth; contaminated food |
Norovirus infection can sweep through families and communities, and it is especially likely to spread among people in confined spaces [1].
Adults infected with rotavirus may not have symptoms but can still spread the illness. This is a particular concern in institutional settings such as nursing homes, because adults with the virus can unknowingly pass it to others. A vaccine against rotavirus gastroenteritis is available in some countries, including the United States, and appears to be effective in preventing the infection [1].
Some shellfish — especially raw or undercooked oysters — can also make you sick, and contaminated drinking water is a cause of viral diarrhea. But in many cases, the virus is passed when someone who is infected handles food you eat without washing their hands after using the toilet [1].
Risk Factors: Who Gets Hit Hardest?
Gastroenteritis occurs all over the world and can affect people of all ages, but some groups are more susceptible [1].
Risk group | Why they are more vulnerable |
|---|---|
Young children | Those in child care centers or elementary schools are especially vulnerable because a child's immune system takes time to mature |
Older adults | Immune systems become less efficient later in life; nursing home residents live in close contact with others who may pass along germs |
Schoolchildren or dormitory residents | Anywhere groups gather in close quarters, intestinal infections pass easily |
People with weakened immune systems | Lower resistance from HIV/AIDS, chemotherapy, or other conditions raises risk substantially |
Each gastrointestinal virus has a season when it is most active. If you live in the Northern Hemisphere, you are more likely to have rotavirus or norovirus infections in the winter and spring [1].
When to See a Doctor
Most healthy people recover from viral gastroenteritis without complications, but certain signs mean you need medical attention [1].
Adults
Call your health care provider if you:
Cannot keep liquids down for 24 hours
Have been vomiting or having diarrhea for more than two days
Are vomiting blood
Are dehydrated — signs include excessive thirst, dry mouth, deep yellow urine or little or no urine, and severe weakness, dizziness, or lightheadedness
Notice blood in your bowel movements
Have severe stomach pain
Have a fever above 104 F (40 C)
Children
See your child's health care provider right away if your child:
Has a fever of 102 F (38.9 C) or higher
Seems tired or very irritable
Is in a lot of discomfort or pain
Has bloody diarrhea
Seems dehydrated — compare how much your child drinks and urinates with what is normal for them, and watch for dry mouth, thirst, and crying without tears
Infants
Spitting up may be an everyday occurrence for your baby, but vomiting is not. Call your baby's doctor right away if your baby:
Has frequent vomiting
Hasn't had a wet diaper in six hours
Has bloody stools or severe diarrhea
Has a sunken soft spot (fontanel) on the top of the head
Has a dry mouth or cries without tears
Is unusually sleepy, drowsy, or unresponsive
Complications: Dehydration Is the Real Danger
The main complication of viral gastroenteritis is dehydration — a severe loss of water and essential salts and minerals. If you are healthy and drink enough to replace the fluids you lose from vomiting and diarrhea, dehydration shouldn't be a problem [1].
Infants, older adults, and people with weakened immune systems may become severely dehydrated when they lose more fluids than they can replace. Hospitalization might be needed so that lost fluids can be replaced through an IV in the arm, and dehydration can rarely lead to death [1]. This is why the recovery guidance below focuses so heavily on fluid replacement.
Diagnosis: How Stomach Flu Is Confirmed
Your doctor will likely diagnose viral gastroenteritis based on your symptoms, a physical exam, and sometimes the presence of similar cases in your community [2].
Diagnostic step | What it involves |
|---|---|
Symptoms and exam | Diagnosis is usually based on symptoms, a physical exam, and sometimes similar cases in the community |
Rapid stool test | Can detect rotavirus or norovirus, but there are no quick tests for other viruses that cause gastroenteritis |
Stool sample | In some cases, submitted to rule out a possible bacterial or parasitic infection |
Treatment: Why Antibiotics Don't Help — and What Does
There is often no specific medical treatment for viral gastroenteritis. Antibiotics aren't effective against viruses, so treatment first involves self-care measures, such as staying hydrated [2].
Self-Care for Adults
To keep yourself more comfortable and prevent dehydration while you recover, try the following [2]:
Self-care step | What to do |
|---|---|
Let your stomach settle | Stop eating solid foods for a few hours |
Replace fluids | Suck on ice chips or take small sips of water often; also try clear soda, clear broths, or noncaffeinated sports drinks; oral rehydration solutions can help. Drink plenty of liquid every day, in small, frequent sips |
Ease back into eating | Return to your normal diet as you're able; start with bland, easy-to-digest foods such as soda crackers, soup, oats, noodles, bananas, and rice; stop eating if nausea returns |
Avoid until you feel better | Caffeine, alcohol, nicotine, and fatty or highly seasoned foods |
Get plenty of rest | The illness and dehydration may have left you weak and tired |
Anti-diarrhea medications | Some adults find loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol) helpful — but avoid these if you have bloody diarrhea or fever, which could be signs of another condition |
Self-Care for Infants and Children
When your child has an intestinal infection, the most important goal is to replace lost fluids and salts [2]:
Step | What to do |
|---|---|
Rehydrate with oral rehydration solution | Available at pharmacies without a prescription; ask your doctor how to use it |
Don't give plain water | In children with gastroenteritis, water isn't absorbed well and won't adequately replace lost electrolytes |
Avoid apple juice | It can make diarrhea worse |
Return to a normal diet once hydrated | Toast, yogurt, fruits, and vegetables |
Avoid sugary foods | Ice cream, sodas, and candy can make diarrhea worse |
Plenty of rest | The illness and dehydration can leave your child weak and tired |
Skip store-bought anti-diarrheal medications | Unless advised by your doctor — they can make it harder for your child's body to get rid of the virus |
For a sick infant, let the baby's stomach rest for 15 to 20 minutes after vomiting or a bout of diarrhea, then offer small amounts of liquid. If you're breast-feeding, let your baby nurse. If your baby is bottle-fed, offer a small amount of an oral rehydration solution or regular formula — don't dilute your baby's already-prepared formula [2].
Prevention: Handwashing Is the Heavy Lifter
Because there is no effective treatment for the virus itself, prevention is key. Avoid food and water that may be contaminated, and wash your hands thoroughly and often [1].
Prevention measure | Specific guidance |
|---|---|
Vaccinate infants | The rotavirus vaccine, given in the first year of life, appears effective at preventing severe symptoms (available in some countries, including the United States) |
Wash hands thoroughly | After using the toilet, after changing diapers, and before preparing or eating food; use warm water and soap, rubbing well for at least 20 seconds, around cuticles, beneath fingernails, and in the creases of the hands; carry sanitizing wipes and hand sanitizer for when soap and water aren't available |
Use separate personal items | Don't share eating utensils, drinking glasses, or plates; use separate towels in the bathroom |
Prepare food safely | Wash all fruits and vegetables; clean kitchen surfaces before preparing food; don't prepare food if you're sick |
Keep your distance | Avoid close contact with anyone who has the virus, if possible |
Disinfect hard surfaces | Use 5–25 tablespoons (73–369 mL) of household bleach per gallon (3.8 L) of water on counters, faucets, and doorknobs |
Handle laundry carefully | Wear gloves when touching potentially exposed laundry; wash clothing and bedding in hot water and dry on the hottest setting; wash your hands afterward |
Check your child care center | Separate rooms for diaper changing and food preparation; the diaper room should have a sink and a sanitary way to dispose of diapers |
When Traveling
When you travel to other countries, you can become sick from contaminated food or water. You may reduce your risk by following these tips [1]:
Drink only well-sealed bottled or carbonated water
Avoid ice cubes, which may be made from contaminated water
Use bottled water to brush your teeth
Avoid raw food touched by human hands — peeled fruits, raw vegetables, and salads
Avoid undercooked meat and fish
Conclusion: Rest, Fluids, and Patience
Viral gastroenteritis — the stomach flu — is miserable but, for most healthy people, short-lived. It is an intestinal infection, not the respiratory flu, and it arrives as watery diarrhea, cramps, nausea, and vomiting, usually within a day or three of exposure and usually gone within a day or two [1].
Because antibiotics don't touch viruses, the real work of recovery is yours to do at home: replace lost fluids, give your stomach a rest, and ease back into bland foods. The one complication worth watching closely is dehydration — and the warning signs for adults, children, and infants listed in this guide tell you exactly when to move from home care to a doctor's visit [2].
Next steps: If you're fighting the stomach bug right now, start with the hydration steps above and watch for dehydration signs. If symptoms last more than two days, you can't keep liquids down, or you see blood or a high fever, contact a health care provider. To stop the bug from spreading through your home, follow the handwashing and surface-disinfection steps in the prevention section. For more on keeping food safe, see our guide on food poisoning and foodborne illness.
Frequently Asked Questions
What is viral gastroenteritis?
Viral gastroenteritis, commonly called stomach flu, is an intestinal infection that causes watery diarrhea, stomach cramps, nausea or vomiting, and sometimes fever. It is caused by viruses — not the influenza virus that causes respiratory flu [1].
Is stomach flu the same as the regular flu?
No. Influenza affects only the respiratory system — nose, throat, and lungs — while gastroenteritis attacks the intestines. The two illnesses share the "flu" name but are caused by different viruses and affect different body systems [1].
How long does viral gastroenteritis last?
Symptoms usually last just a day or two, though occasionally they may last up to 14 days. They typically begin within 1 to 3 days after infection and range from mild to severe [1].
What causes stomach flu?
Most often you get it by eating or drinking contaminated food or water, or through contact with an infected person. The main culprits are norovirus — the most common cause of foodborne illness worldwide — and rotavirus, the most common cause in children [1].
Is there a cure for viral gastroenteritis?
There is often no specific medical treatment, and antibiotics do not work against viruses. Recovery relies on self-care: staying hydrated, letting your stomach settle, and easing back into bland foods while the virus runs its course [2].
What should you drink with the stomach bug?
Try ice chips or small, frequent sips of water, clear soda, clear broths, or noncaffeinated sports drinks. Oral rehydration solutions can also help. For children, use oral rehydration solution — not plain water, which isn't absorbed well, and not apple juice, which can worsen diarrhea [2].
Can you take anti-diarrhea medication for stomach flu?
Some adults find loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol) helpful. Avoid them if you have bloody diarrhea or fever, which could signal another condition. Do not give store-bought anti-diarrheal medications to children unless a doctor advises it [2].
How can you prevent viral gastroenteritis?
Wash your hands thoroughly with soap and warm water for at least 20 seconds — especially after the toilet, after diaper changes, and before handling food. Don't share utensils or towels, wash fruits and vegetables, disinfect hard surfaces with a bleach solution, and keep your distance from anyone who is sick [1].
Is viral gastroenteritis dangerous?
For otherwise healthy people, recovery usually happens without complications. But it can be deadly for infants, older adults, and people with weakened immune systems, mainly through dehydration. Seek care for dehydration signs, blood in stool or vomit, or high fever [1].
Can you get stomach flu again after recovering?
Yes. Many different viruses cause gastroenteritis, and each has a season when it is most active — in the Northern Hemisphere, rotavirus and norovirus infections are more likely in the winter and spring [1]. Immunity to one virus does not protect you from the others.
Related Reading
Food Poisoning (Foodborne Illness): Symptoms, the 16 Common Causes, and How to Recover Safely at Home — what to know when contaminated food makes you sick
References
Source currency note: Both Mayo Clinic pages were published/updated on April 30, 2025, and the three studies were checked against PubMed. This article reflects the most current information available from those sources.
Mayo Clinic Staff. Viral gastroenteritis (stomach flu) - Symptoms & causes. Mayo Clinic. April 30, 2025. https://www.mayoclinic.org/diseases-conditions/viral-gastroenteritis/symptoms-causes/syc-20378847
Mayo Clinic Staff. Viral gastroenteritis (stomach flu) - Diagnosis & treatment. Mayo Clinic. April 30, 2025. https://www.mayoclinic.org/diseases-conditions/viral-gastroenteritis/diagnosis-treatment/drc-20378852
Ejemot-Nwadiaro RI, Ehiri JE, Arikpo D, et al. Hand-washing promotion for preventing diarrhoea. Cochrane Database of Systematic Reviews. 2021;12(1):CD004265. PMID 33539552. https://doi.org/10.1002/14651858.CD004265.pub4
Sun ZW, Fu Y, Lu HL, et al. Association of rotavirus vaccines with reduction in rotavirus gastroenteritis in children younger than 5 years: a systematic review and meta-analysis of randomized clinical trials and observational studies. JAMA Pediatrics. 2021;175(7):e210347. PMID 33970192. https://doi.org/10.1001/jamapediatrics.2021.0347
Hartling L, Bellemare S, Wiebe N, et al. Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children. Cochrane Database of Systematic Reviews. 2006;2006(3):CD004390. PMID 16856044. https://doi.org/10.1002/14651858.CD004390.pub2
Further reading
Centers for Disease Control and Prevention. Norovirus. CDC. Accessed October 11, 2026. https://www.cdc.gov/norovirus/
Centers for Disease Control and Prevention. Rotavirus. CDC. Accessed October 11, 2026. https://www.cdc.gov/rotavirus/index.html
National Institute of Diabetes and Digestive and Kidney Diseases. Viral gastroenteritis ("stomach flu"). NIDDK. Accessed October 11, 2026. https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/definition-facts
Medical disclaimer
Health information, not medical advice. This article is for general education and is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider about your own health, and seek emergency care for urgent symptoms.
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