Diphenhydramine Dosing for a 6-Year-Old Child Weighing 28.4kg
The appropriate dose of Benadryl (diphenhydramine) for a 6-year-old child weighing 28.4kg with a concentration of 6.25mg/5mL is 28-35mg (22.5-28mL) every 6 hours as needed, not to exceed 4 doses in 24 hours.
Dosing Calculation
The FDA-approved dosing for diphenhydramine follows these guidelines:
- For children 6-12 years: 25mg (10mL of 6.25mg/5mL solution) per dose 1
- Weight-based dosing: 1-2mg/kg per dose (maximum 50mg) every 6 hours 2
For this 28.4kg child:
- At 1mg/kg: 28.4mg (rounded to 28mg)
- At 2mg/kg: 56.8mg (exceeds the 50mg maximum dose for children)
- Using the 6.25mg/5mL concentration:
- 28mg dose = 22.5mL
- 35mg dose = 28mL
Administration Guidelines
- Administer every 6 hours as needed
- Do not exceed 4 doses in 24 hours
- Measure using an oral syringe for accuracy
- Can be given with or without food
Clinical Considerations
Indications
- Allergic reactions
- Allergic rhinitis symptoms
- Urticaria (hives)
Cautions
- Sedation is a significant side effect, especially in children
- May impair cognitive function and psychomotor performance
- Risk of paradoxical excitation in some children
Alternative Options
Consider second-generation antihistamines as they have:
- Similar efficacy with less sedation 3, 4
- Longer duration of action (once daily dosing)
- Lower risk of cognitive impairment
- Examples include cetirizine (5-10mg once daily) or loratadine (10mg once daily) 2
Monitoring
- Monitor for sedation, which can be significant in young children
- Watch for paradoxical excitation (hyperactivity)
- Ensure proper hydration
Important Precautions
- Store medication out of reach of children to prevent accidental overdose
- Do not use with other medications containing diphenhydramine
- Avoid use with other sedating medications
- Discontinue before allergy testing to avoid false-negative results
While diphenhydramine remains widely available, newer second-generation antihistamines generally offer a better safety profile with similar efficacy for most allergic conditions 5. However, for acute management of allergic reactions when a sedating effect might be beneficial, the weight-based dosing of diphenhydramine as calculated above is appropriate.