What is the appropriate management of vomiting in patients of any age?

Treatment of Vomiting in Patients of All Ages

Oral rehydration solution (ORS) is the first-line treatment for vomiting across all age groups with mild to moderate dehydration, while isotonic intravenous fluids are reserved for severe dehydration, shock, altered mental status, or failure of oral rehydration. 1

Initial Assessment and Fluid Management

Mild to Moderate Dehydration

• Administer reduced-osmolarity ORS as first-line therapy for all ages with mild to moderate dehydration (3-9% fluid deficit). 1
• Dosing for rehydration phase:
  • Infants and children: 50-100 mL/kg ORS over 3-4 hours 1
  • Adolescents and adults (≥30 kg): 2-4 liters ORS over 3-4 hours 1
• Replacement of ongoing losses:
  • Children <10 kg: 60-120 mL ORS per vomiting episode (up to ~500 mL/day) 1
  • Children >10 kg: 120-240 mL ORS per vomiting episode (up to ~1 L/day) 1
  • Adolescents and adults: Ad libitum, up to ~2 L/day 1

Severe Dehydration (≥10% Deficit)

• Administer isotonic intravenous crystalloids (lactated Ringer's or normal saline) immediately when severe dehydration, shock, altered mental status, or ileus is present. 1, 2
• Give 20 mL/kg boluses until pulse, perfusion, and mental status normalize. 1
• Malnourished infants may benefit from smaller-volume, frequent boluses of 10 mL/kg due to reduced cardiac capacity. 1
• Continue IV rehydration until the patient awakens, has no aspiration risk, and has no ileus, then transition to ORS for remaining deficit. 1

Alternative Routes When Oral Intake Fails

• Nasogastric ORS administration may be considered in patients with moderate dehydration who cannot tolerate oral intake or are too weak to drink. 1
• In patients with ketonemia, initial IV hydration may be needed before oral rehydration can be tolerated. 1, 2

Antiemetic Therapy: Age-Specific Guidelines

Children < 4 Years

• Antiemetics are NOT routinely recommended in children under 4 years of age. 3
• Ondansetron may increase stool volume and diarrhea frequency, potentially worsening dehydration in young children. 3
• Dimenhydrinate (Gravol) should NOT be used routinely for viral gastroenteritis in children, as it lacks demonstrated efficacy and causes drowsiness and anticholinergic effects. 3

Children ≥ 4 Years and Adolescents

• Ondansetron may be given to facilitate oral rehydration when vomiting is present (weak recommendation, moderate evidence). 1, 3
• Dosing: 0.15 mg/kg IV (maximum 4 mg) or 0.2 mg/kg oral (maximum 4 mg). 4
• Monitor for QTc prolongation, especially when combined with other QT-prolonging agents. 2

Adults

• Initiate dopamine receptor antagonists (metoclopramide, prochlorperazine, or haloperidol) titrated to maximum benefit and tolerance. 2
• Add ondansetron 8-16 mg IV if symptoms persist after 4 weeks or for breakthrough vomiting. 2
• Combine ondansetron with dexamethasone 10-20 mg IV for refractory cases, as this combination is superior to either agent alone. 2
• Administer antiemetics on a scheduled basis rather than as-needed, as prevention is easier than treating established vomiting. 2

Dietary Management

• Continue breastfeeding throughout the illness in infants. 1, 2
• Resume age-appropriate normal diet during or immediately after rehydration is completed. 1, 2
• Do NOT recommend fasting, as this can worsen metabolic derangements and is not beneficial. 5
• Avoid high-sugar fluids (apple juice, sports drinks, soft drinks) for rehydration, as these are inappropriate even in standard gastroenteritis management. 1, 5

Critical Pitfalls to Avoid

• Never use antimotility drugs (loperamide) in children <18 years with acute diarrhea or in any age with inflammatory diarrhea or fever. 1, 2
• Never use antiemetics in suspected mechanical bowel obstruction, as this can mask progressive ileus and gastric distension. 2
• Never delay rehydration while awaiting specialty consultation—treat dehydration first. 5
• Bilious or bloody vomiting requires immediate evaluation for surgical causes; place nasogastric tube for decompression and stop oral intake. 4
• Monitor for extrapyramidal symptoms with dopamine antagonists, particularly in young males, and treat with diphenhydramine 50 mg IV if they develop. 2

Refractory Vomiting: Additional Options

• Metoclopramide 10 mg IV every 6 hours is particularly effective for gastric stasis and can be titrated to maximum benefit. 2
• Haloperidol 1 mg IV/PO every 4 hours as needed is an alternative dopamine antagonist with a different receptor profile. 2
• Dronabinol 2.5-7.5 mg PO every 4 hours as needed is FDA-approved for refractory nausea unresponsive to conventional antiemetics. 2
• Consider adding H2 blocker or proton pump inhibitor if dyspepsia is present, as patients may confuse heartburn with nausea. 2
• Use agents from different drug classes simultaneously rather than sequential monotherapy for refractory cases. 2

Laboratory Monitoring

• Obtain complete blood count, serum electrolytes, glucose, liver function tests, lipase, and urinalysis in patients with persistent vomiting to exclude metabolic causes and assess dehydration. 2
• Correct hypokalemia, hypomagnesemia, and metabolic alkalosis that result from prolonged vomiting. 2
• Serum bicarbonate ≤13 mEq/L predicts higher likelihood of requiring hospitalization and prolonged IV therapy. 6