Hydroxyzine is generally well-tolerated in children when used appropriately, though emerging research raises important safety considerations for long-term use in preschoolers. The most common side effect is sedation, but paradoxical excitation can occur in some children. A 2022 population study found concerning associations between repeated hydroxyzine use and neurodevelopmental disorders in children under 10, highlighting the need for careful risk-benefit assessment in pediatric patients.
The most frequently reported side effect, with drowsiness commonly occurring during initial treatment. Children may experience difficulty concentrating, fatigue, and feeling confused. This effect is dose-dependent and typically more pronounced in the first few doses. Management: Consider timing doses before bedtime when appropriate, and avoid activities requiring alertness. Monitoring: Watch for excessive sedation that interferes with normal activities or development, and report persistent drowsiness beyond initial treatment period.
Dry mouth and thickened secretions occur due to hydroxyzine's anticholinergic properties, though these effects are milder compared to other first-generation antihistamines. Children may also experience constipation and blurred vision. Management: Encourage adequate fluid intake, use sugar-free gum or candy for dry mouth, and ensure proper dental hygiene. Monitoring: Report severe dry mouth affecting eating or speaking, or constipation lasting more than 2-3 days.
Approximately 15% of children may experience paradoxical reactions including irritability, agitation, excitation, or insomnia instead of expected sedation. This effect is more common in younger children and may occur with delayed onset. Management: Discontinue medication and contact healthcare provider immediately if paradoxical reactions occur. Alternative treatments should be considered. Monitoring: Watch for unusual hyperactivity, irritability, or sleep disturbances, especially in children under 6 years.
Hydroxyzine can cause QT prolongation and potentially life-threatening torsade de pointes, particularly in children with underlying risk factors. Between 1955-2016, 59 cases of QT prolongation were reported across all ages. Management: Maximum pediatric dose should not exceed 2 mg/kg/day in children ≤40 kg. Avoid in children with known cardiac conditions or electrolyte imbalances. Monitoring: Watch for palpitations, fainting, or unusual fatigue, and ensure electrolyte balance is maintained.
A 2022 population study found that repeated hydroxyzine prescriptions in children increased risk of tic disorders (OR 1.55), anxiety (OR 1.34), and conduct disturbances (OR 1.34) compared to single prescriptions. This represents the first evidence of potential long-term neurodevelopmental effects. Management: Use shortest effective duration, especially in preschool children. Consider alternative treatments for chronic conditions. Monitoring: Regular developmental assessments during treatment, and report any new behavioral changes or tics.
Hydroxyzine adverse effects in children include sedation (most common), anticholinergic effects (dry mouth, constipation), and rarely paradoxical excitation (~15% in post-sedation studies). Serious concerns include QT prolongation risk and emerging evidence of neurodevelopmental effects with repeated use (1.55x increased tic risk, 1.34x increased anxiety/conduct disorders in population study of children under 10).
3 documented effects
4-6 hours; may persist longer in children
Time doses appropriately; avoid activities requiring alertness; consider bedtime dosing when possible
Watch for excessive sedation interfering with normal activities; report persistent drowsiness
Variable; until drug clearance
Discontinue medication immediately; consider alternative treatments; supportive care
Watch for unusual hyperactivity, irritability, agitation, or insomnia instead of expected sedation
Resolves as drug clears
Dose timing adjustment; avoid complex tasks during peak effect
Report persistent confusion or significant cognitive impairment
2 documented effects
Throughout treatment period
Increase fluid intake; sugar-free gum or candy; maintain dental hygiene
Report severe dry mouth affecting eating, speaking, or dental health
During treatment period
Increase fiber and fluid intake; encourage physical activity
Report constipation lasting >2-3 days or severe abdominal discomfort
1 documented effect
Until drug clearance and correction of contributing factors
Maximum 2 mg/kg/day in children ≤40kg; monitor electrolytes; avoid in cardiac disease
Watch for palpitations, fainting, unusual fatigue; baseline and follow-up ECG if risk factors
1 documented effect
Potentially persistent; requires further study
Use shortest effective duration; consider alternatives for chronic conditions; regular developmental monitoring
Monitor for development of tics, increased anxiety, or behavioral changes during and after treatment
Age under 6 years (increased risk of paradoxical excitation and neurodevelopmental effects)
Underlying cardiac conditions or family history of sudden cardiac death
Electrolyte imbalances (hypokalemia, hypomagnesemia)
Concomitant QT-prolonging medications
Repeated or prolonged use (increased neurodevelopmental risk)
Use lowest effective dose for shortest duration; monitor electrolytes if risk factors present; avoid in children with cardiac conditions; consider second-generation antihistamines for chronic use; ensure proper hydration; time doses to minimize impact on daily activities
📞 Call your pediatrician immediately if you notice any of these symptoms:
Paradoxical excitation (agitation, hyperactivity, insomnia instead of sedation)
Cardiac symptoms (palpitations, fainting, chest pain, unusual fatigue)
Severe anticholinergic effects (inability to urinate, severe constipation, high fever)
New onset of tics, unusual anxiety, or behavioral changes
Allergic reactions (rash, hives, swelling, difficulty breathing)
Excessive sedation interfering with normal activities or development
| Effect | Hydroxyzine | Cetirizine (second-generation antihistamine) |
|---|---|---|
| Sedation | High (first-generation) | Minimal (second-generation) |
| Anticholinergic effects | Moderate | Minimal |
| Neurodevelopmental safety | Concerning (new evidence) | No evidence of harm in 18-month study |
Additive risk of QT prolongation and torsade de pointes; avoid concurrent use
Enhanced sedation and respiratory depression risk; use with extreme caution
Additive anticholinergic effects including increased dry mouth and constipation
Clinical assessment framework
Parent and clinician concerns about Hydroxyzine