Diphenhydramine (Benadryl) Dosing for a 1-Year-Old Child
For a 1-year-old child weighing 24 pounds (approximately 11 kg), the recommended dose of liquid diphenhydramine (Benadryl) is 11-22 mg (or 4.4-8.8 mL of the standard 12.5 mg/5 mL liquid formulation) every 6 hours as needed. 1
Dosage Calculation
The appropriate dosing for diphenhydramine in children follows these guidelines:
- Standard pediatric dosing: 1-2 mg/kg per dose 1
- For a 24-pound (11 kg) child:
- Minimum dose: 11 mg (1 mg/kg × 11 kg)
- Maximum dose: 22 mg (2 mg/kg × 11 kg)
Liquid Formulation Conversion
Most liquid diphenhydramine (Benadryl) comes in a concentration of 12.5 mg per 5 mL:
- Minimum dose (11 mg): 4.4 mL
- Maximum dose (22 mg): 8.8 mL
Administration Guidelines
- Give every 6 hours as needed 1
- Do not exceed 4 doses in 24 hours
- Use for short-term treatment only (2-3 days) to avoid tolerance development and side effects 1
- Use an oral syringe or dosing cup for accurate measurement - never use household spoons
Important Precautions
- Monitor closely for sedation - this is the most common side effect in young children 1
- Watch for paradoxical excitation or agitation, which can occur in infants instead of sedation 1
- Avoid combining with other medications that cause drowsiness
- Discontinue if excessive sedation, difficulty breathing, or unusual behavior occurs
- Not recommended for routine use as a sleep aid in children
Common Side Effects to Monitor
- Drowsiness/sedation (most common)
- Dry mouth
- Irritability or paradoxical excitation
- Thickened bronchial secretions
- Urinary retention
Cautions
- Diphenhydramine should be used with caution in young children and only when clearly needed 1
- The American Academy of Allergy, Asthma, and Immunology recommends limiting first-generation antihistamines like diphenhydramine to short courses (2-3 days) due to side effects 1
- Adverse events from diphenhydramine in children commonly result from accidental unsupervised ingestions, with most cases occurring in children 2-4 years of age 2
- Store medication securely out of children's reach to prevent accidental overdose
Remember that accurate dosing is critical in pediatric patients, as children are not simply "small adults" and require individualized dosing based on weight 3, 4.