What is the recommended adult route and dosing of hydroxyzine (Atarax) for anxiety, pruritus, sedation, insomnia, and pre‑ or post‑operative use in patients without significant hepatic, renal, or cardiac impairment?

Hydroxyzine (Atarax) Adult Dosing and Routes

For adults without significant organ impairment, hydroxyzine is administered orally or intramuscularly at doses ranging from 25-100 mg depending on the indication: 25 mg three to four times daily for pruritus, 50-100 mg four times daily for anxiety, and 50-100 mg as a single dose for preoperative sedation. 1

Route of Administration

• Oral route is preferred for most indications and should be used for maintenance therapy 1
• Intramuscular (IM) route may be used for treatment initiation, with subsequent doses transitioned to oral administration 1
• Intravenous administration is not an approved route for hydroxyzine 1

Dosing by Indication

Anxiety and Tension (Psychoneurosis)

• Standard dose: 50-100 mg four times daily (QID) for symptomatic relief of anxiety associated with psychoneurosis or organic disease states 1
• Clinical trials have demonstrated efficacy at a fixed dose of 50 mg daily in generalized anxiety disorder, with superiority over placebo evident from the first week of treatment 2, 3
• Anxiolytic effects commence during the first week and are maintained throughout 4 weeks of treatment without rebound anxiety upon abrupt discontinuation 3

Pruritus (Allergic Conditions)

• Standard dose: 25 mg three to four times daily (TID or QID) for management of pruritus due to chronic urticaria, atopic dermatitis, contact dermatoses, and histamine-mediated pruritus 1
• This lower dose reflects the antihistaminic properties required for pruritus control 4

Sedation and Preoperative Use

• Preoperative sedation: 50-100 mg as a single dose when used as premedication 1
• Postoperative sedation: 50-100 mg as needed following general anesthesia 1
• Studies comparing hydroxyzine 75 mg with other premedicants demonstrate safety and efficacy, though anxiolytic effects are modest 5

Insomnia (Off-Label)

• Bedtime dosing: 25-50 mg at bedtime for short-term treatment of insomnia 6
• Evidence suggests hydroxyzine could be considered when previous therapy was ineffective, not tolerated, or contraindicated, though data are limited to short-term use 6
• The most common adverse effect is transient sleepiness, which typically appears during the first week and progressively diminishes 3

Dose Adjustment Principles

• Dosage should be adjusted according to the patient's response to therapy, as with all potent medications 1
• When initiating treatment via IM route, transition to oral administration for subsequent doses 1

Important Safety Considerations

Hepatic Impairment

• Hydroxyzine should be avoided in severe liver disease due to its sedating effects being inappropriate in this population 4
• The medication is hepatotoxic and may precipitate coma in severe hepatic disease 4

Renal Impairment

• Dose should be halved in moderate renal impairment (creatinine clearance 10-20 mL/min) 4
• Avoid use in severe renal impairment (creatinine clearance <10 mL/min) 4

Pregnancy

• Hydroxyzine is specifically contraindicated during early pregnancy according to UK manufacturer guidelines 4
• It is the only antihistamine with this specific contraindication, though avoidance of all antihistamines in the first trimester is generally recommended 4

Cardiac Considerations

• Hydroxyzine is metabolized to cetirizine, which may be sedating, especially at higher doses 4
• No specific QT prolongation warnings exist for hydroxyzine, unlike some other antihistamines 4

Common Adverse Effects

• Sleepiness/drowsiness (28% vs 14% placebo) is the most common side effect, typically transient and appearing during the first week 3
• Dry mouth (14% vs 5% placebo) 3
• Weight gain (12% vs 10% placebo) 3
• Loss of concentration (9% vs 8% placebo) 3
• Overall, side effects were reported in 52% of hydroxyzine-treated patients versus 35% with placebo 3

Clinical Pearls

• Hydroxyzine demonstrates lack of organ toxicity and absence of dependency based on extensive clinical experience 2
• No rebound anxiety or withdrawal symptoms occur after abrupt discontinuation following 4 weeks of treatment 3
• The medication shows greater and more rapid cognitive improvement compared to lorazepam in some controlled trials 2
• For urticaria management, hydroxyzine 10-50 mg at night may be added to a non-sedating antihistamine during the day to help patients sleep better 4