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Antihistamine (H1) — Anxiolytic / Sedative Pregnancy: Avoid — particularly in first trimester and peripartum (neonatal withdrawal, QT effects). Use with extreme caution only if clearly necessary near term.

Hydroxyzine

Brand names: Atarax, Ucerax

Adult dose

Dose: Anxiety (short-term): 25mg TDS–QDS; maximum 100mg QDS (300mg daily). Pruritus: 25mg at bedtime; may increase to 25mg TDS–QDS. Pre-operative sedation: 50–100mg oral 30–60 minutes before procedure.
Route: Oral
Frequency: Three to four times daily (anxiety); once nightly (pruritus)
Max: 300mg daily (anxiety); 100mg at night (pruritus)
H1 receptor antagonist with additional anxiolytic properties — likely via anticholinergic and antihistaminergic CNS sedation. NICE recommends hydroxyzine as an option for short-term GAD treatment when SSRIs not tolerated. Non-addictive — no dependence potential. Maximum single dose in elderly: 50mg. Onset within 30 minutes (faster than buspirone). QTc prolongation — MHRA restriction on maximum dose.

Paediatric dose

Dose: 0.5 mg/kg
Route: Oral
Frequency: Three to four times daily
Max: 2mg/kg/day or 100mg/day (whichever lower)
BNFc: Pruritus: 6 months–5 years: 5–15mg daily in divided doses; 6–17 years: 15–25mg at night up to 50–100mg in divided doses. Anxiety in children: seek specialist child and adolescent psychiatry opinion. Avoid under 6 months.

Dose adjustments

Renal

Reduce dose in renal impairment — active metabolite (cetirizine) accumulates; increase dosing interval.

Hepatic

Reduce dose in hepatic impairment and extend dosing interval.

Paediatric weight-based calculator

BNFc: Pruritus: 6 months–5 years: 5–15mg daily in divided doses; 6–17 years: 15–25mg at night up to 50–100mg in divided doses. Anxiety in children: seek specialist child and adolescent psychiatry opinion. Avoid under 6 months.

Clinical pearls

  • MHRA 2015: maximum dose restricted to 100mg QDS (adults) due to QTc prolongation risk — ECG recommended at baseline if cardiac risk factors
  • Advantage over benzodiazepines: no dependence, no withdrawal, no abuse potential — suitable for patients with a history of substance dependence who need anxiolytic treatment
  • Metabolised to cetirizine (antihistamine) — may explain some of its ongoing antipruritic effects; cetirizine can be used if hydroxyzine sedation is problematic in pruritus
  • Short-term use preferred — not ideal for long-term anxiety management (sedation becomes problematic and tolerance to anxiolytic effect may develop)

Contraindications

  • QT prolongation or risk factors for long QT
  • Congenital long QT syndrome
  • Porphyria
  • Hypersensitivity to hydroxyzine, cetirizine, or aminophylline

Side effects

  • Sedation (therapeutic)
  • Dry mouth (anticholinergic)
  • Dizziness
  • Headache
  • QTc prolongation (dose-dependent — MHRA 2015 restriction)
  • Urinary retention (anticholinergic — caution in BPH)
  • Paradoxical agitation (elderly)

Interactions

  • CNS depressants, opioids, alcohol — additive sedation
  • QT-prolonging drugs — additive QTc prolongation (avoid combination)
  • Anticholinergic drugs — additive effects (urinary retention, dry mouth, confusion)

Monitoring

  • QTc (ECG — baseline if risk factors)
  • Anticholinergic side effects (urinary symptoms, constipation)
  • Sedation severity
  • Anxiety symptom response

Reference: BNFc; BNF 90; NICE NG106 (GAD); MHRA Hydroxyzine Safety Update 2015. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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