Diphenhydramine (Benadryl) Dosing in Pediatrics
Diphenhydramine should NOT be used in children under 6 years of age for routine indications, and when used in children 6 years and older, the dose is 1-2 mg/kg per dose (maximum 50 mg per dose) every 4-6 hours. 1, 2, 3
Critical Age-Based Restrictions
Children Under 6 Years
- The FDA explicitly states that diphenhydramine products should not be used in children under 6 years of age 3
- Between 1969-2006, diphenhydramine was responsible for 33 deaths in children under 6 years, with 41 total antihistamine deaths occurring in children under 2 years 1
- The FDA's Nonprescription Drugs and Pediatric Advisory Committees recommend that OTC cough and cold medications (including first-generation antihistamines like diphenhydramine) no longer be used in children below 6 years of age 1
Neonates and Infants
- Diphenhydramine is absolutely contraindicated in neonates due to severe risks including respiratory suppression, sedation, hypotension, paradoxical excitement, and seizures (especially with rapid IV administration) 4
- The American Academy of Pediatrics does not include specific dosing recommendations for diphenhydramine in neonates, and existing recommendations should not be extrapolated to this age group 4
Dosing for Children ≥6 Years
Standard Dosing
- 1-2 mg/kg per dose, with a maximum single dose of 50 mg 1, 2
- Administer every 4-6 hours as needed 3
- Do not exceed 6 doses in 24 hours (maximum 300 mg daily) 3
Age-Specific Guidelines
- Children 6 to under 12 years: 10 mL (25 mg) per dose 3
- Children 12 years and older: 10-20 mL (25-50 mg) per dose 3
- For infants and young children (if used under direct medical supervision in emergency contexts), use the lower end of the dosing range (1 mg/kg) 2
Special Clinical Contexts
Anaphylaxis Management
- Diphenhydramine is SECOND-LINE therapy to epinephrine and should never be administered alone 2
- Dose: 1-2 mg/kg or 25-50 mg per dose (maximum 50 mg) 2
- Liquid oral formulations are absorbed more rapidly than tablets in acute allergic reactions 2
- Combination with ranitidine (1 mg/kg) is superior to diphenhydramine alone 2
Acute Behavioral Emergencies (Adolescents)
- Used in combination protocols for chemical restraint in emergency settings 5
- Adolescent dosing in combination with antipsychotics: typically part of haloperidol + diphenhydramine or risperidone + diphenhydramine protocols 5
- Close monitoring required for respiratory depression, hypotension, and paradoxical behavioral disinhibition 5
Administration Considerations
Route and Formulation
- Liquid formulations are preferred in young children for easier administration and better absorption 1, 2
- Oral liquid formulations are more readily absorbed than tablets when used for acute allergic reactions 2
Safety Monitoring
- Monitor for sedation and respiratory suppression, especially if using other sedative agents concurrently 2
- Rapid IV administration may precipitate seizures; administer slowly when using parenteral routes 2
- May cause paradoxical excitation or agitation in some pediatric patients 2
Critical Pitfalls to Avoid
Dosing Errors
- Never exceed 50 mg per single dose regardless of weight 2
- Do not use combination OTC cough and cold products in children under 6 years due to overdose risk 1
- Toxicity threshold: Children ingesting ≥7.5 mg/kg should be referred to an emergency department 6
Inappropriate Use
- Do not use diphenhydramine "to make a child sleepy" - this is explicitly contraindicated per FDA labeling 1
- Avoid in children with anticholinergic delirium or intoxication from drugs with anticholinergic properties 5
- Should not be used for prevention of wheezing or asthma in infants with atopic dermatitis 1
Preferred Alternatives
Second-generation antihistamines (cetirizine, loratadine, desloratadine, fexofenadine, levocetirizine) are strongly preferred over diphenhydramine for routine allergic symptoms in all pediatric age groups due to superior safety profiles, fewer sedating effects, and lower risk of central nervous system toxicity 1, 4