Hydroxyzine

Hydroxyzine is a first-generation antihistamine with anxiolytic, sedative, and anticholinergic properties. It is used in the treatment of anxiety, insomnia, pruritus, and as an adjunct in allergic and psychoneurotic conditions.

• Drug class: H1-antihistamine (first-generation)
• ATC code: N05BB01
• Subtypes:
  • Hydroxyzine hydrochloride (Atarax®)
  • Hydroxyzine pamoate (Vistaril®)

• Antagonist at histamine H1 receptors in the CNS and periphery
• Also has effects on muscarinic, serotonergic, and dopaminergic receptors
• Produces sedation, anxiolysis, and antiemetic effects

• Anxiety disorders (short-term treatment)
• Preoperative sedation
• Insomnia (off-label)
• Urticaria and pruritus
• Allergic rhinitis
• Tinnitus-related distress (off-label)

• Anxiety: 25–50 mg up to 4 times daily
• Pruritus: 25 mg at night or every 6–8 hours
• Sedation: 50–100 mg at bedtime
• Titrate based on sedation and tolerability

• Common: Drowsiness, dry mouth, headache, dizziness, blurred vision
• Anticholinergic: Constipation, urinary retention, confusion (especially in elderly)
• Rare but serious: QT prolongation, seizures (at high doses)

• Hypersensitivity to hydroxyzine or cetirizine (its active metabolite)
• Prolonged QT interval or history of torsades de pointes
• First trimester of pregnancy (teratogenic risk)

• Use with caution in elderly (Beers Criteria)
• Avoid in renal or hepatic impairment without dose adjustment
• Caution with other CNS depressants (alcohol, opioids, benzodiazepines)

• CNS depressants: Additive sedation
• QT-prolonging drugs: Increased risk of arrhythmia
• MAO inhibitors: Avoid concomitant use

• Considered a non-addictive alternative to benzodiazepines for anxiety or sleep
• Onset of action: ~15–30 minutes
• May impair psychomotor performance; avoid driving

• Hydroxyzine hydrochloride: Atarax®
• Hydroxyzine pamoate: Vistaril®
• Metabolite: Cetirizine (second-generation antihistamine)

• Antihistamines
• Anxiolytic medications
• Pharmacological management of insomnia
• Tinnitus and pharmacologic modulation