Food, water, and what to do when something didn't sit right.

The default pattern of foodborne illness

Most viral and bacterial foodborne illness causes 24 to 72 hours of nausea, vomiting, and diarrhea, sometimes with low-grade fever and cramping. Symptoms typically peak in the first 12–24 hours and improve thereafter. The single most useful safety metric is hydration.

Hydration first, always

• Sip frequently — small, frequent volumes are absorbed better than large gulps when nauseated.
• An oral rehydration solution beats plain water when losses are heavy.
• Watch urine output, color, and dizziness on standing as your dashboard.

Patterns that change the tier

• High fever (≥102°F) persistent over 24 hours.
• Blood in stool — bright red or black/tarry.
• Severe abdominal pain, particularly in the lower right or upper right.
• Symptoms beyond 72 hours with no improvement, or relapse.
• Inability to keep any fluid down for >12 hours.
• High-risk individuals: infants, older adults, pregnancy, immunocompromised — escalate sooner.

Suspected food poisoning vs. viral GI

You usually cannot tell at the symptom level. Time-of-onset relative to a suspect meal can hint at it (most bacterial toxins hit within 1–6 hours; viral GI usually takes 12–48). Either way, the management is the same: hydrate, rest, and watch for the red flags above.

Travelers' diarrhea and travel water safety

• In areas with unfamiliar water systems, default to bottled or boiled water for drinking and brushing teeth.
• Avoid ice from unknown sources, raw produce washed in tap water, and undercooked seafood or meat.
• Carry oral rehydration salts when traveling.
• Consider talking to a travel-medicine clinician before high-risk trips about whether antibiotic standby therapy is appropriate for you.

Domestic water concerns

• If your area issues a boil-water notice, take it seriously: boil water for at least one minute (longer at altitude), or use bottled.
• For cloudy or off-tasting tap water without a notice, contact your water utility — it is usually a flushing or maintenance issue, not a health emergency.
• Lead concerns are real in older housing; a simple home test or filtered water for cooking and drinking is reasonable in older buildings.

Children, infants, and pregnancy

• Infants dehydrate fast. No wet diaper for 6–8 hours, lethargy, or sunken soft spot is an urgent-care issue.
• Pregnancy raises the stakes for listeria, salmonella, and severe dehydration — escalate sooner than for a non-pregnant adult.
• Children with persistent vomiting and lethargy should not "wait it out" past 24 hours without a clinician.

Related: Exposure Hub · Travel Risk · Stomach Symptoms.