What is the typical dosing for hydroxyzine (antihistamine)?

Hydroxyzine Dosing

For adults with pruritus from allergic conditions, use hydroxyzine 25 mg three to four times daily; for anxiety, use 50-100 mg four times daily; and for children under 6 years, use 50 mg daily in divided doses regardless of indication. 1

Standard Adult Dosing

Pruritus Management (Allergic Conditions)

• Adults: 25 mg three to four times daily for management of pruritus due to chronic urticaria, atopic dermatitis, and contact dermatoses 1
• Hydroxyzine is particularly useful when added at night to a non-sedating antihistamine regimen, leveraging its sedating properties for better sleep while controlling symptoms 2

Anxiety Management

• Adults: 50-100 mg four times daily for symptomatic relief of anxiety and tension associated with psychoneurosis 1
• Research supports 50 mg/day as producing statistically significant anxiolytic effects beginning in the first week of treatment 3

Preoperative Sedation

• Adults: 50-100 mg as premedication before or after general anesthesia 1

Pediatric Dosing

Children Under 6 Years

• 50 mg daily in divided doses for all indications (pruritus, anxiety) 1

Children Over 6 Years

• 50-100 mg daily in divided doses for all indications 1

Preoperative Sedation (Pediatric)

• 0.6 mg/kg of body weight 1

Dosing Strategy to Minimize Side Effects

Evening or bedtime dosing (50 mg at bedtime) significantly reduces daytime psychomotor impairment while maintaining therapeutic efficacy. 4 This strategy:

• Maintains H1-receptor antagonism the following morning 4
• Alleviates prolongation of reaction times seen with divided doses 4
• Reduces but does not eliminate subjective drowsiness 4

The British Journal of Dermatology specifically recommends combining hydroxyzine at night with non-sedating antihistamines during the day for optimal urticaria management 2

Critical Dosing Adjustments

Renal Impairment

• Moderate renal impairment: Reduce dose by 50% 2
• Severe renal impairment (CrCl <10 mL/min): Avoid hydroxyzine entirely 2

Hepatic Impairment

• Severe liver disease: Avoid hydroxyzine due to enhanced sedating effects 2

Pregnancy

• Contraindicated in early pregnancy; if antihistamine therapy is necessary during pregnancy, chlorphenamine is preferred due to its long safety record 2

Important Clinical Caveats

CNS Depression and Performance Impairment

• Hydroxyzine significantly prolongs both simple and choice reaction times without development of tolerance over 5 days 5
• Avoid concomitant use with other CNS depressants as this enhances performance impairment 2
• Subjective symptoms (drowsiness, dry mouth) are unreliable predictors of objective performance impairment—patients may feel fine but still have impaired reaction times 5
• Recent data shows hydroxyzine is increasingly identified in impaired driving investigations, with common observations including incoordination, slurred speech, and difficulty following instructions 6

Combination Therapy

• For refractory urticaria not responding to hydroxyzine alone, adding an H2-antagonist (such as cimetidine) may provide better control 2

Tolerance Development

• The most common side effect is transient sleepiness, which appears during the first week and progressively diminishes during continued treatment 3
• However, objective psychomotor impairment does NOT demonstrate tolerance development over at least 5 days 5