How to treat nausea in a 16-year-old?

Treatment of Nausea in a 16-Year-Old

For a 16-year-old with nausea, first assess for dehydration and gastroenteritis as the most likely cause in this age group, then use ondansetron 8 mg orally to control vomiting and facilitate oral rehydration if needed. 1, 2, 3

Initial Assessment

The priority is determining whether this is acute gastroenteritis with dehydration versus another cause:

• Check hydration status immediately by examining for sunken eyes, decreased skin turgor, dry mucous membranes, decreased urine output, tachycardia, and abnormal capillary refill, as these are the most useful predictors of significant dehydration 1, 4
• Ask about recent fluid intake and output, vomiting frequency, diarrhea, fever, and abdominal pain to distinguish gastroenteritis from other causes 5
• Review current medications (especially opioids if applicable) and assess for other red flags including severe abdominal pain, bilious vomiting, blood in vomit or stool, or altered mental status 1, 2

Treatment Algorithm for Gastroenteritis-Related Nausea

If Mild to Moderate Dehydration Present:

• Begin oral rehydration solution (ORS) with small, frequent volumes starting at 5 mL every minute using a spoon or syringe, gradually increasing as tolerated 6, 1
• Replace ongoing losses by giving 10 mL/kg of ORS for each episode of vomiting or diarrhea 1
• Administer ondansetron 8 mg orally to facilitate tolerance of oral rehydration and reduce immediate need for hospitalization, as this is recommended for children >4 years of age with persistent vomiting 6, 1, 3
• Note that ondansetron may increase stool volume/diarrhea as a side effect, but this does not outweigh its benefit in controlling vomiting 1

If Severe Dehydration or Inability to Tolerate Oral Fluids:

• Administer intravenous isotonic fluids (lactated Ringer's or normal saline) until pulse, perfusion, and mental status normalize 6, 1
• Continue IV rehydration until the patient can tolerate oral intake, then transition to ORS for remaining deficit replacement 6

Treatment for Non-Gastroenteritis Nausea

If gastroenteritis is excluded and nausea persists:

• Start with dopamine receptor antagonists such as prochlorperazine 10 mg orally every 6 hours as needed, metoclopramide 10-20 mg orally every 6 hours, or olanzapine 2.5-5 mg orally 2
• Consider serotonin (5-HT3) receptor antagonists like ondansetron 8 mg orally daily or twice daily if dopamine antagonists are insufficient 2, 3
• If nausea persists despite as-needed regimen, administer antiemetics around the clock for 1 week, then change to as-needed dosing 2
• Add medications with different mechanisms such as antihistamines (meclizine) or anticholinergic agents (scopolamine transdermal patch 1 mg/3 days) for refractory symptoms 2

Nutritional Management

Once adequately hydrated:

• Resume normal age-appropriate diet immediately without delaying for 24 hours, as early refeeding improves outcomes 6, 1
• Offer starches, cereals, yogurt, fruits, and vegetables while avoiding foods high in simple sugars and fats 6, 1
• Continue lactose-containing foods unless clinical worsening occurs, as presence of reducing substances in stool alone does not indicate lactose intolerance 6, 1

Critical Pitfalls to Avoid

• Do not use antimotility drugs (loperamide) in patients <18 years of age with acute diarrhea, as this is contraindicated 6
• Do not withhold antiemetics while waiting for rehydration if vomiting prevents oral intake, as ondansetron specifically facilitates oral rehydration 1, 4
• Do not delay refeeding once rehydrated, as this worsens nutritional status without benefit 1

When to Escalate Care

Instruct the patient/family to return immediately if:

• The patient becomes increasingly lethargic or difficult to arouse 1
• Urine output decreases significantly 1
• Intractable or bilious vomiting develops 1
• Blood appears in vomit or stool 1
• Severe abdominal pain or worsening symptoms occur despite treatment 1