What is the appropriate use and dosage of hydroxyzine (antihistamine) for a 15-year-old?

Hydroxyzine Use in 15-Year-Olds

For a 15-year-old, hydroxyzine is appropriate for anxiety and allergic conditions at a dose of 50-100 mg daily in divided doses, though caution is warranted given emerging safety concerns about long-term neurodevelopmental effects and cardiac risks in pediatric populations. 1

FDA-Approved Dosing for Adolescents

For patients over 6 years of age (which includes 15-year-olds), the FDA-approved dosing is: 1

• Anxiety/tension: 50-100 mg daily in divided doses 1
• Pruritus (allergic conditions): 50-100 mg daily in divided doses 1
• Premedication/sedation: 0.6 mg/kg body weight 1

The dosage should be adjusted according to the patient's response to therapy. 1

Primary Indications

Hydroxyzine is a sedating first-generation antihistamine approved for: 2, 1

• Anxiolysis in children and adolescents 2
• Allergic conditions including chronic urticaria and atopic dermatitis 1
• Preoperative sedation 1
• Management of pruritus 1

Critical Safety Considerations

Cardiac Risk

A case report documented supraventricular tachycardia in a 9-year-old on clinical doses of hydroxyzine, with the arrhythmia resolving after discontinuation. 3 This represents a rare but serious adverse effect requiring monitoring, particularly in adolescents with any cardiac history. 3

Neurodevelopmental Concerns

Recent population-based data suggest that repeat prescriptions of hydroxyzine in young children are associated with increased rates of tics, anxiety disorders, and conduct disturbances. 4 While this study focused on preschool children, the findings raise concerns about prolonged use in any pediatric population. The study found odds ratios of 1.55 for tic disorders, 1.34 for anxiety, and 1.34 for conduct disturbances with repeat prescriptions versus single prescriptions. 4 Therefore, use the shortest possible duration when prescribing hydroxyzine to adolescents. 4

Common Side Effects

The most frequent adverse effect is drowsiness/sleepiness, occurring in approximately 28% of patients (versus 14% with placebo). 5 This typically appears during the first week and progressively diminishes with continued treatment. 5 Other side effects include: 5

• Dry mouth (14% vs 5% placebo) 5
• Weight gain (12% vs 10% placebo) 5
• Loss of concentration (9% vs 8% placebo) 5

Contraindications and Dose Adjustments

Renal Impairment

Halve the dose in moderate renal impairment (creatinine clearance 10-20 mL/min). 2, 6 Avoid hydroxyzine entirely in severe renal impairment (creatinine clearance <10 mL/min). 2, 6

Hepatic Impairment

Avoid hydroxyzine in severe liver disease due to its sedating effects being inappropriate in this context. 2, 6

Pregnancy Considerations

Hydroxyzine is specifically contraindicated during early pregnancy. 2, 6 This is relevant for sexually active adolescent females who should be counseled accordingly. 2

Clinical Efficacy

For generalized anxiety disorder, hydroxyzine demonstrates superiority over placebo from the first week of treatment, with maintained efficacy throughout 4 weeks and no rebound anxiety after abrupt discontinuation. 5 However, a Cochrane review concluded that due to high risk of bias in available studies, hydroxyzine cannot be recommended as a reliable first-line treatment for GAD. 7

Practical Prescribing Algorithm

1. Confirm indication: Anxiety, pruritus, or allergic conditions 1
2. Screen for contraindications: Cardiac history, severe renal/hepatic impairment, pregnancy 2, 3
3. Start with standard dosing: 50-100 mg daily in divided doses 1
4. Warn about drowsiness: Particularly during the first week; avoid driving or operating machinery 5
5. Limit duration: Use shortest effective course given neurodevelopmental concerns 4
6. Monitor for cardiac symptoms: Palpitations, chest tightness, or tachycardia warrant immediate discontinuation 3
7. Avoid CNS depressants: Do not combine with benzodiazepines or other sedatives 6

Alternative Considerations

For anxiety in adolescents, consider non-sedating antihistamines for daytime use, reserving hydroxyzine for nighttime if sedation is beneficial. 6 For urticaria not responding to hydroxyzine alone, adding an H2-antagonist may provide better control. 2, 6