Diphenhydramine (Benadryl) Dosing for Children
For children, diphenhydramine should be dosed at 1-2 mg/kg/dose every 4-6 hours as needed, with a maximum of 50 mg per dose, and should NOT be used in children under 6 years of age without physician guidance. 1, 2
Age-Based Dosing Guidelines
- Children under 6 years of age: Do not use without physician guidance 2
- Children 6 to under 12 years of age: 10 mL (25 mg) every 4-6 hours 2
- Children 12 years and older: 10-20 mL (25-50 mg) every 4-6 hours 2
Important Administration Rules
- Do not exceed 6 doses in 24 hours 2
- Liquid formulations are more readily absorbed than tablets and are preferred for children 1
- When weight-based dosing is needed, use 1-2 mg/kg per dose 1
Safety Considerations
- Diphenhydramine is the most common cause of adverse events associated with cough and cold medications in children 3
- Most adverse events involve accidental unsupervised ingestions (74.7%), particularly in children 2-4 years of age 3
- Common adverse effects include:
- Tachycardia (53.4%)
- Hallucinations (46.5%)
- Somnolence (34.7%)
- Agitation (33.9%)
- Mydriasis (26.3%) 3
Special Situations
For Anaphylaxis Management
- Diphenhydramine is considered second-line therapy at 1-2 mg/kg per dose (maximum 50 mg) 1
- Epinephrine should always be administered first in anaphylaxis 1
- Never use diphenhydramine alone to treat anaphylaxis 1
For Parenteral Administration
- In emergency situations requiring IV administration: 1-2 mg/kg per dose with maximum of 50 mg 1
Clinical Cautions
- Many experts now recommend second-generation antihistamines over diphenhydramine due to:
- Diphenhydramine has a higher adverse side-effect profile in children 5
- Ensure safe storage to prevent accidental ingestions, which are the most common cause of diphenhydramine-related adverse events in children 3
Remember that while diphenhydramine can be effective for allergic symptoms and as a sleep aid 6, newer antihistamines may offer similar benefits with fewer risks, especially for children.