What is causing my dizziness, nausea, and loss of appetite after eating?

Acute Gastroenteritis with Dehydration

You most likely have acute gastroenteritis (food poisoning) causing dehydration, and you need immediate fluid replacement and antiemetic therapy to prevent worsening prerenal azotemia.

Most Likely Diagnosis

Your symptoms—dizziness, nausea, and loss of appetite starting 5 hours after eating a green apple and following a Vietnamese meal—strongly suggest acute gastroenteritis (food poisoning). The timing of symptom onset (within hours of eating) and the constellation of gastrointestinal symptoms point to foodborne illness 1. Your recent travel to the Canary Islands with exposure to different foods and water sources increases your risk for gastroenteritis 1.

Immediate Management Required

Fluid Resuscitation

• Administer 0.9% normal saline 1 liter IV over the first hour to rapidly restore intravascular volume and reverse prerenal azotemia 2
• Continue isotonic saline infusion at a slower rate for the following 24-48 hours with frequent monitoring 2
• If you cannot access IV fluids immediately, drink small frequent amounts of water or oral rehydration solution (water with salt and sugar) 1

Antiemetic Therapy

• Ondansetron 8-16 mg orally is the first-line antiemetic for nausea and vomiting 1, 3
• If vomiting prevents oral intake, ondansetron 8 mg IV can be given over 2-5 minutes and repeated every 4-6 hours as needed 2, 3
• Alternative agents include metoclopramide 10 mg IV or prochlorperazine 5-10 mg IV every 6-8 hours if ondansetron is unavailable 4, 5

Why You Feel This Way

Gastrointestinal Mechanisms

• Gastric irritation and inflammation from contaminated food directly triggers nausea through vagal afferent fibers to the vomiting center in your brain 1, 4
• Gastroparesis (delayed stomach emptying) causes feelings of fullness and recurring nausea that comes in waves 4
• The chemoreceptor trigger zone in your brain becomes periodically activated as your body processes toxins, causing waves of nausea 4

Dehydration Effects

• Dizziness results from volume depletion reducing blood flow to your brain, especially when standing 1
• Your body is losing fluids through vomiting and reduced oral intake, leading to prerenal azotemia (elevated BUN from dehydration) 2

Dietary Management During Recovery

What to Eat Now

• Small, frequent, bland meals following the BRAT diet: bananas, rice, applesauce, and toast 1, 6
• Focus on high-protein, low-fat meals at room temperature to minimize strong odors 6
• Avoid spicy, fatty, acidic, and fried foods 6

Timing of Food Intake

• Wait at least 2 hours after eating before any physical activity to allow proper digestion 1
• Eating increases blood flow requirements to your intestinal tract, and during activity, your muscles may compete for blood supply, resulting in cramps, nausea, or faintness 1

Critical Warning Signs

Seek Emergency Care If You Experience:

• Persistent vomiting preventing any fluid intake for more than 24 hours 2
• Severe dizziness or fainting when standing, indicating significant dehydration 1
• Decreased urination or dark-colored urine, suggesting worsening dehydration 2
• Fever, severe abdominal pain, or bloody stools, which may indicate more serious infection 1

Additional Supportive Measures

Gastric Acid Suppression

• Consider proton pump inhibitors or H2 blockers if gastric irritation is contributing to persistent nausea 1, 4
• These medications help reduce stomach acid production and allow the gastric lining to heal 1

Monitoring

• Check for electrolyte abnormalities, particularly hypokalemia and metabolic alkalosis that commonly develop with protracted vomiting 2
• Monitor fluid intake and output to assess response to treatment 2

Common Pitfalls to Avoid

• Do not delay fluid resuscitation—your clinical presentation of nausea, vomiting, and dizziness mandates immediate fluid therapy 2
• Avoid oral medications when actively vomiting, as the oral route is not feasible; use IV or sublingual routes instead 2
• Do not exercise or engage in physical activity until symptoms resolve and you are adequately rehydrated 1
• Do not consume alcohol, as it can precipitate heat stress and worsen dehydration through effects on vasomotor tone and volume status 1