What is stomach flu?
"Stomach flu" is a misnomer — it's not influenza, but viral gastroenteritis, an inflammation of the stomach and intestines from viruses like norovirus, rotavirus, or adenovirus. Sudden vomiting, diarrhea, abdominal cramps, and sometimes low-grade fever and body aches define it.
Most healthy adults recover in 1–3 days. The main risk is dehydration, especially in young children, older adults, and those with chronic conditions.
Norovirus is the most common cause of adult viral gastroenteritis in the US, infamous for outbreaks on cruise ships, in nursing homes, and at family gatherings. It's extremely contagious — surfaces, food, and droplets all transmit it.
Do I have stomach flu? Common signs
If most of these describe what you're experiencing, telehealth is a reasonable next step:
What causes it
Norovirus is responsible for most adult viral gastroenteritis in the US. Other viruses include rotavirus (more often kids), adenovirus, astrovirus, and sapovirus. Transmission is fecal-oral — contaminated food, water, surfaces, or person-to-person. Outbreaks are common in close-contact settings.
Non-viral causes that may look similar: bacterial food poisoning (Salmonella, E. coli, Campylobacter), parasitic infections (giardia), food intolerance, and inflammatory bowel disease flares.
Is it contagious?
Yes — norovirus especially. You're contagious during the illness and for several days after symptoms resolve. Tiny amounts of virus are infectious. Hand washing with soap and water (alcohol sanitizer is less effective against norovirus), cleaning surfaces with bleach-based products, and avoiding food preparation for others until 2 days symptom-free reduce spread.
Small, frequent sips beat large gulps — your stomach can usually handle a teaspoon every few minutes when nothing else stays down.
Can it be treated online?
Telehealth handles stomach flu well. A clinician assesses dehydration, rules out red flags (severe abdominal pain, bloody diarrhea, high fever, signs of intestinal blockage), and provides guidance on oral rehydration. Anti-nausea medication like ondansetron (Zofran) can be prescribed when vomiting prevents fluid intake — this often keeps people out of the ER for IV fluids.
How stomach flu is treated
Fluid replacement is the cornerstone: small, frequent sips of oral rehydration solution (Pedialyte) or clear electrolyte drinks. Avoid plain water exclusively — you need sodium and glucose for absorption.
Ondansetron (Zofran): a sublingual anti-nausea medication that can stop vomiting and let you keep fluids down. Often prescribed by telehealth.
Loperamide (Imodium): can be used for adult viral diarrhea after the first day or so. Avoid in bloody diarrhea or significant fever (may worsen bacterial colitis).
Antibiotics: generally NOT for viral gastroenteritis. Considered only when bacterial cause is suspected.
Self-care while you wait
- Take small, frequent sips — a teaspoon every few minutes if needed
- Use oral rehydration solution (Pedialyte) or sport drinks
- Slowly add back bland foods (BRAT diet — bananas, rice, applesauce, toast)
- Avoid dairy, caffeine, alcohol, fatty foods until recovered
- Rest
- Wash hands frequently with soap and water
- Disinfect surfaces with bleach-based cleaner
- Don't prepare food for others until 48 hours symptom-free
How long does it last?
Most healthy adults recover in 1–3 days. Some viral causes (like norovirus) can last up to a week. If diarrhea lasts more than a week, or is accompanied by significant blood, weight loss, or systemic symptoms, get in-person evaluation — could be a different process.
Frequently asked questions
How do I know if I'm dehydrated?
Dry mouth, decreased urination, dark concentrated urine, dizziness on standing, lethargy, increased heart rate. Severe dehydration warrants ER evaluation.
When should I take Zofran?
Ondansetron is most useful when vomiting prevents you from holding down fluids. A sublingual dose 30 minutes before trying fluids often lets you keep liquids down.
Can I take Imodium for stomach flu diarrhea?
For uncomplicated viral diarrhea in adults, loperamide can help. Avoid if you have bloody diarrhea, high fever, or are immunocompromised — could worsen bacterial colitis.
Why is my whole family getting sick?
Norovirus is extremely contagious and spreads fast in households. Aggressive hand washing, surface disinfection with bleach products, and avoiding shared food preparation help.
Is it stomach flu or food poisoning?
Both look similar. Food poisoning often presents more acutely (within hours of eating) and may involve everyone who shared the meal. Bacterial food poisoning may have more blood in stool or higher fever. Often, treatment is similar — supportive care.
