What are the indications, dosing regimens, side effects, and contraindications for hydroxyzine in adults and children?

Hydroxyzine: Clinical Overview

Indications

Hydroxyzine is FDA-approved for anxiety/tension, pruritus from allergic conditions, and as preoperative/postoperative sedation, with specific dosing varying by indication and age. 1

Primary Indications:

• Anxiety and tension associated with psychoneurosis and as adjunct in organic disease states 1
• Pruritus management in allergic conditions including chronic urticaria, atopic dermatitis, contact dermatoses, and histamine-mediated pruritus 1
• Sedation for premedication and following general anesthesia 1

Guideline-Supported Uses:

• Urticaria: Hydroxyzine 10-50 mg at night can be added to nonsedating antihistamines to help patients sleep, though it adds little additional effect on urticaria control if H1 receptors are already saturated 2
• Generalized pruritus of unknown origin (GPUO): Sedative antihistamines like hydroxyzine are recommended only short-term or in palliative settings 3
• NOT recommended for pruritus in elderly skin due to safety concerns 3

Dosing Regimens

Adults:

• Anxiety/tension: 50-100 mg four times daily 1
• Pruritus: 25 mg three to four times daily 1
• Preoperative sedation: 50-100 mg 1
• Urticaria (off-label nighttime use): 10-50 mg at bedtime 2

Children:

• Under 6 years: 50 mg daily in divided doses (for both anxiety and pruritus) 1
• Over 6 years: 50-100 mg daily in divided doses (for both anxiety and pruritus) 1
• Preoperative sedation: 0.6 mg/kg body weight 1
• Atopic dermatitis: 0.7 mg/kg three times daily is as effective as 1.4 mg/kg three times daily with significantly less sedation 4

Dosing Adjustments:

• Renal impairment: Halve the dose in moderate renal impairment (creatinine clearance 10-20 mL/min); avoid in severe renal impairment (creatinine clearance <10 mL/min) 2
• Hepatic impairment: Avoid in severe liver disease due to inappropriate sedating effects 2

Dosing Strategy to Minimize Side Effects:

Bedtime dosing of hydroxyzine 50 mg maintains antihistamine efficacy while mitigating daytime psychomotor impairment compared to divided doses. 5

Side Effects

Common Adverse Effects:

• Sedation/drowsiness: Most common, occurring in 28% of patients, typically appears during first week and progressively diminishes 6
• Dry mouth: Reported in 14% of patients 6
• Weight gain: 12% of patients 6
• Loss of concentration: 9% of patients 6
• Insomnia: 9% of patients 6
• Irritability 5

Serious Concerns:

• CNS depression: Can cause fatigue, sedation, impaired memory, concentration, and psychomotor function 7
• Driving impairment: Clinical studies and DUID investigations demonstrate hydroxyzine impairs driving performance, with observations including erratic driving, crashes, and difficulty with coordination 7
• QT prolongation risk: Contraindicated in patients with prolonged QT interval 1

Pharmacokinetics in Children:

• Peak serum concentration of 47.4 ng/mL occurs at 2 hours after 0.7 mg/kg oral dose 4
• Elimination half-life is 7.1 hours (increases with age) 4
• Pruritus suppression >85% from 2-12 hours post-dose 4

Contraindications

Absolute Contraindications:

• Known hypersensitivity to hydroxyzine, cetirizine, or levocetirizine 1
• Prolonged QT interval 1
• Early pregnancy: Hydroxyzine is specifically contraindicated in early pregnancy as it induced fetal abnormalities in animal studies at doses above human therapeutic range 2, 1
• Severe liver disease: Sedating effect is inappropriate 2
• Severe renal impairment (creatinine clearance <10 mL/min) 2

Relative Contraindications and Cautions:

• Pregnancy (all trimesters): Best to avoid, though chlorphenamine often chosen when antihistamine necessary due to long safety record 2
• Lactation: Avoidance or caution recommended 2
• Elderly patients with pruritus: Should not be prescribed sedative antihistamines due to safety concerns 3
• Concurrent medications: Use caution with other CNS depressants given additive effects 7

Clinical Context:

In DUID investigations, 74% of hydroxyzine-positive drivers also had antidepressants, 44% had opioids, and 38% had anticonvulsants, highlighting dangerous polypharmacy patterns. 7 Only seven single-substance cases were identified, emphasizing the importance of screening for drug combinations 7.

Efficacy Notes:

• Anxiety: Hydroxyzine 50 mg/day produces statistically and clinically significant anxiolytic effects starting in the first week, maintained through 4 weeks, without rebound anxiety or withdrawal symptoms upon abrupt discontinuation 6
• Insomnia: Mixed efficacy demonstrated for sleep onset, maintenance, and quality; may be considered short-term when previous therapy ineffective, not tolerated, or contraindicated 8