Diphenhydramine Should Not Be Given to Infants Under 1 Year Old
Diphenhydramine is contraindicated in infants under 12 months of age due to documented fatalities, lack of efficacy, and significant safety concerns. The FDA drug label explicitly warns against use "in neonates or premature infants," and multiple professional guidelines strongly recommend avoiding all OTC cough and cold medications, including first-generation antihistamines like diphenhydramine, in children below 6 years of age 1, 2.
Critical Safety Evidence
Mortality Data
Between 1969 and 2006, there were 69 fatalities associated with antihistamines in children ≤6 years, with diphenhydramine accounting for 33 deaths and 41 of these fatalities occurring in children under 2 years of age 1.
Fatal intoxications have been documented in infants as young as 6,8,9, and 12 weeks old, with postmortem blood diphenhydramine levels (1.1-1.6 mg/L) that were lower than levels seen in adult fatalities, indicating heightened vulnerability in this age group 3.
A 3-month-old infant with Trisomy 21 suffered cardiac arrest immediately following a single 1.25 mg/kg intravenous dose of diphenhydramine 4.
Lack of Efficacy
A randomized controlled trial (the TIRED study) in infants aged 6-15 months demonstrated that diphenhydramine was no more effective than placebo for reducing nighttime awakenings or improving sleep, with only 1 of 22 children showing improvement compared to 3 of 22 receiving placebo 5.
The trial was stopped early by the data safety monitoring board due to lack of effectiveness 5.
Guideline Recommendations
Professional Society Position
The FDA's Nonprescription Drugs and Pediatric Advisory Committees recommended in 2007 that OTC cough and cold medications no longer be used for children below 6 years of age 1. This recommendation was based on:
- Lack of established efficacy for symptomatic treatment of upper respiratory tract infections in children younger than 6 years 1
- Potential toxicity of these medications 1
- Common overdose errors from use of multiple products, medication errors, accidental exposures, and intentional overdose 1
Market Response
In October 2007, major pharmaceutical manufacturers (Wyeth, Novartis, Prestige Brands, and Johnson & Johnson) voluntarily removed their cough and cold medications for children under age 2 years from the OTC market 1.
Safer Alternatives
Second-generation antihistamines (cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine) have been shown to be well tolerated with a very good safety profile when used in young children 1. These agents should be considered instead when antihistamine therapy is truly indicated.
Special Circumstances: Anaphylaxis
Even in anaphylaxis management, diphenhydramine has limitations in infants:
- Diphenhydramine is considered second-line therapy to epinephrine and should never be administered alone in the treatment of anaphylaxis 6.
- The recommended dose for anaphylaxis is 1-2 mg/kg parenterally 6, but this must be weighed against the documented risks in infants under 1 year.
- H1 antihistamines have a much slower onset of action than epinephrine 6.
Common Pitfalls to Avoid
Do not use diphenhydramine for sedation in infants - it can cause paradoxical CNS stimulation ranging from excitation to seizures and death 3.
Avoid the misconception that "over-the-counter" means "safe for all ages" - the FDA label explicitly contraindicates use in neonates 2.
Do not rely on diphenhydramine for sleep issues in infants - controlled trials demonstrate no benefit over placebo 5.
Be aware that toxic levels in infants are lower than in adults - postmortem levels in fatal infant cases were significantly lower than typical adult fatalities 3.