How Long Does a Stomach Bug Last?

Quick Answer

A stomach bug (viral gastroenteritis) typically lasts 1–3 days when caused by norovirus, the most common culprit. Rotavirus infections tend to last 3–8 days and primarily affect young children. Bacterial gastroenteritis from contaminated food can persist for 1–2 weeks. Most healthy adults recover fully without medical treatment.

Duration by Cause

Cause	Duration	Key Symptoms	Prevalence
Norovirus	1–3 days	Sudden vomiting, watery diarrhea, cramping	Most common cause in adults
Rotavirus	3–8 days	Watery diarrhea, fever, vomiting	Most common in children under 5
Adenovirus	5–12 days	Diarrhea, low-grade fever, mild respiratory symptoms	More common in children
Astrovirus	3–4 days	Mild watery diarrhea, low-grade fever	Primarily affects young children and elderly
Salmonella	4–7 days	Diarrhea, fever, abdominal cramps	Contaminated food (poultry, eggs)
E. coli	5–10 days	Severe cramps, bloody diarrhea (some strains)	Contaminated food or water
Campylobacter	2–10 days	Diarrhea (often bloody), fever, cramping	Undercooked poultry
Food poisoning (S. aureus)	1–3 days	Rapid-onset vomiting, cramping	Toxin-mediated, often from prepared foods

Symptom Timeline (Norovirus)

Phase	Timeframe	What to Expect
Incubation	12–48 hours after exposure	No symptoms yet, but contagious
Onset	Hours 0–6	Sudden nausea, vomiting begins, watery diarrhea
Peak	Hours 6–24	Most severe vomiting and diarrhea, possible low-grade fever
Improving	Day 2	Vomiting subsides, diarrhea slows, appetite begins returning
Resolution	Day 2–3	Symptoms resolve, mild fatigue may linger
Post-recovery	Up to 2 weeks	Still shedding virus in stool (contagious)

Dehydration: The Main Danger

The primary risk from a stomach bug is not the infection itself but dehydration from fluid loss through vomiting and diarrhea. Watch for these signs of dehydration:

In adults: Dark urine, reduced urination, dry mouth, dizziness when standing, rapid heartbeat

In children: No wet diapers for 3+ hours, no tears when crying, sunken eyes, dry mouth, listlessness

In infants: Sunken fontanelle (soft spot), no wet diapers for 6+ hours, extreme fussiness or unusual sleepiness

How to Manage a Stomach Bug

Hydration Strategy

• Sip small amounts frequently rather than drinking large volumes at once
• Oral rehydration solutions (ORS) like Pedialyte are ideal — they replace electrolytes and sugar in the right ratio
• Clear broths, diluted juice, and flat ginger ale are acceptable alternatives
• Avoid dairy, caffeine, and alcohol until fully recovered

Eating During Recovery

The traditional BRAT diet (bananas, rice, applesauce, toast) is no longer specifically recommended by most pediatric organizations, but these foods remain easy to tolerate. Resume a normal diet as soon as you can keep food down — bland, low-fat foods first, then gradually return to regular meals.

What Not to Take

• Anti-diarrheal medications (loperamide) may prolong bacterial infections by preventing the body from expelling the pathogen. Use only for viral gastroenteritis and only in adults.
• Antibiotics are ineffective against viral gastroenteritis and unnecessary for most bacterial cases.

Contagiousness

Norovirus is extremely contagious. As few as 18 viral particles can cause infection. The virus spreads through contaminated food or water, person-to-person contact, and touching contaminated surfaces. Infected individuals remain contagious for at least 48 hours after symptoms resolve and can shed the virus in stool for up to two weeks.

To prevent spreading: wash hands thoroughly with soap and water (hand sanitizer is less effective against norovirus), clean contaminated surfaces with bleach-based cleaners, wash soiled laundry on the hottest setting, and avoid preparing food for others until 48 hours after symptoms end.

When to See a Doctor

Seek medical care if diarrhea lasts more than 3 days, if you see blood in stool or vomit, if fever exceeds 104°F (40°C), if you cannot keep any fluids down for 24 hours, or if you show signs of severe dehydration. Children under 5, adults over 65, pregnant women, and immunocompromised individuals should seek care earlier.