Promethazine Dosing for a 4-Year-Old Child
Promethazine is contraindicated for children under 2 years of age, and for a 4-year-old child, the recommended dose for motion sickness is 0.5 mg per pound of body weight (approximately 0.5-1.1 mg/kg), administered 12.5 to 25 mg twice daily. 1
FDA-Approved Dosing Guidelines
- Promethazine is FDA-approved for children 2 years and older, with a black box warning specifically contraindicating its use in children under 2 years 1
- For a 4-year-old child, dosing is weight-based at 0.5 mg per pound of body weight 1
- For motion sickness: 12.5 to 25 mg twice daily, with the initial dose taken 30-60 minutes before travel and repeated 8-12 hours later if needed 1
- For nausea and vomiting: 0.5 mg per pound of body weight, adjusted to the child's age, weight, and condition severity 1
- For sedation: 12.5 to 25 mg at bedtime 1
Important Safety Considerations
Promethazine has been associated with significant adverse effects in children, including:
- Respiratory depression
- Sedation
- Agitation
- Hallucinations
- Seizures
- Dystonic reactions 2
The FDA drug label specifically warns about respiratory depression risks in pediatric patients 1
Administration Recommendations
- Available forms include tablets, syrup, and suppositories 1
- For young children, the liquid formulation is typically easier to administer with appropriate measuring devices 1
- Doses may be repeated at 4-6 hour intervals as necessary, depending on the indication 1
Clinical Pearls and Cautions
- Weight-based dosing is critical for pediatric patients to avoid overdosing 3
- Children weighing more than 40 kg should be dosed as adults 4
- Promethazine should be used with caution in children due to its potential for significant adverse effects 2
- Consider alternative antiemetics with better safety profiles in young children when possible 2
- Monitor the child closely for sedation, respiratory depression, and extrapyramidal symptoms after administration 2
Specific Dosing Algorithm
- Calculate the child's weight in pounds
- Multiply weight by 0.5 mg to determine the appropriate dose
- Do not exceed 25 mg per dose for a 4-year-old child 1
- Administer no more frequently than every 4-6 hours as needed 1
- Do not exceed 75 mg total daily dose for a 4-year-old 1
Remember that promethazine should be used judiciously in young children, and only when the benefits clearly outweigh the risks of adverse effects.