What should I do if I experience nausea and vomiting after eating oysters?

Acute Gastroenteritis from Contaminated Oysters

If you develop nausea and vomiting within 1-4 hours after eating oysters at a buffet, this most likely represents viral gastroenteritis (particularly Norovirus/Norwalk virus) or bacterial food poisoning, and you should focus on aggressive oral rehydration, monitor for signs of severe infection, and seek immediate medical attention if you develop fever, severe abdominal pain, bloody diarrhea, or signs of sepsis.

Immediate Assessment and Risk Stratification

Critical Red Flags Requiring Emergency Evaluation

• Seek immediate emergency care if you develop fever, severe abdominal pain, skin lesions/bullae, or signs of septic shock (hypotension, altered mental status, extreme lethargy), as these may indicate life-threatening Vibrio vulnificus or Aeromonas hydrophila septicemia 1, 2, 3
• Patients with chronic liver disease (from alcohol use, hepatitis B/C, or cirrhosis) face a >50% mortality rate from V. vulnificus septicemia after raw oyster consumption and require immediate IV antibiotics (doxycycline plus a third-generation cephalosporin) 1, 3
• The onset of V. vulnificus infection is typically 24-48 hours after consumption, with rapid progression to septic shock within 36 hours 3

Most Likely Diagnosis: Viral Gastroenteritis

• Norwalk virus (Norovirus) is the most common cause of oyster-associated gastroenteritis, presenting with nausea (100%), vomiting (83%), and diarrhea (50%) with an incubation period of approximately 42 hours 4, 5
• Symptoms typically resolve completely within 36-48 hours without specific treatment 4
• The symptom complex matches the common "24-hour stomach flu" 5

Initial Management Strategy

Hydration and Supportive Care

• Maintain adequate fluid intake of at least 1.5 L/day to prevent dehydration, which accounts for one-third of emergency room visits within 3 months of gastrointestinal illness 6, 7
• Monitor for signs of dehydration including decreased urine output, dizziness, dry mucous membranes, and tachycardia 6
• Small, frequent sips of clear fluids are better tolerated than large volumes 7

Antiemetic Therapy

• Initiate metoclopramide 10 mg orally every 6-8 hours as first-line therapy for persistent vomiting, as it provides both antiemetic effects and promotes gastric emptying 7, 8
• If vomiting prevents oral intake, consider prochlorperazine 25 mg rectal suppository or seek medical care for IV antiemetics 7
• Add ondansetron 4-8 mg orally/sublingually if symptoms persist after 4 hours, though be aware this may increase diarrhea volume 7

Laboratory Evaluation if Symptoms Persist Beyond 24-48 Hours

• Obtain complete blood count, serum electrolytes, glucose, and liver function tests to exclude metabolic causes and assess for dehydration 7
• Prolonged vomiting can cause hypokalemia, hypochloremia, and metabolic alkalosis requiring correction 7

When to Seek Medical Attention

Immediate Emergency Care Needed If:

• Fever develops (suggests bacterial infection requiring antibiotics) 1, 2, 3
• Skin lesions or bullae appear (pathognomonic for V. vulnificus) 3
• Severe abdominal pain or signs of peritonitis develop 6
• Bloody diarrhea occurs 6
• Signs of dehydration despite oral rehydration (decreased urine output, orthostatic hypotension, altered mental status) 6, 7
• You have underlying liver disease, immunosuppression, or chronic illness 1, 3

Urgent Medical Evaluation Needed If:

• Vomiting persists beyond 24 hours despite antiemetics 7
• Unable to tolerate any oral fluids for >6-8 hours 6
• Symptoms worsen rather than improve after 24-48 hours 4

Special Considerations and Pitfalls

Critical Populations at High Risk

• Patients with chronic liver disease (alcoholic cirrhosis, hepatitis B/C) must seek immediate medical care even with mild symptoms, as V. vulnificus septicemia carries >50% mortality in this population 1, 3
• Fifteen of 16 cases in Los Angeles County occurred in patients with preexisting liver disease, and all were septicemic 3

Thiamin Supplementation

• If vomiting persists for >2-3 weeks, initiate thiamin supplementation to prevent Wernicke's encephalopathy 6, 7

Avoid These Common Mistakes

• Do not use antiemetics if mechanical bowel obstruction is suspected, as this can mask progressive ileus 7
• Do not assume symptoms are "just food poisoning" if you have liver disease—this requires immediate medical evaluation 1, 3
• Do not use ondansetron as monotherapy in early stages, as it may worsen diarrhea; combine with a dopamine antagonist 7

Expected Clinical Course

Typical Viral Gastroenteritis Timeline

• Symptom onset: 24-48 hours after oyster consumption 4, 5
• Peak symptoms: First 24 hours 4
• Complete resolution: 36-48 hours from onset 4
• If symptoms persist beyond 72 hours or worsen, seek medical evaluation for possible bacterial infection 1, 2