Hydroxyzine

General

• Type: Antihistamines / H1 blocker
• Dosage Forms: Oral, IM
• Common Trade Names: Atarax

Adult Dosing

• Anxiety
  • PO: 50-100mg q6h PRN
  • IM: 50-100mg q4-6h PRN

• Allergic reaction or Pruritus
  • PO: 25mg q6-8h

• Nausea/Vomiting
  • IM: 25-100mg q6-8h PRN

• Insomnia
  • PO: 50-100mg PO qhs
  • IM: 50mg qhs

Pediatric Dosing

• Anxiety or Pruritus
  • <6 yo
    • PO: 50mg/day divided into q6-8h PRN
  • 6-12 yo
    • PO: 50-100mg/day divided into q6-8h PRN
  • >12 yo
    • See adult dosing

• Nausea/Vomiting
  • IM: 1.1mg/kg/dose

Special Populations

• Pregnancy Rating: No human data available
• Renal Dosing: CrCl <50: decrease usual dose by 50%
• Hepatic Dosing: n/a
• High-risk geriatric medication!

Contraindications

• Allergy to class/drug
• Elderly patients
• QT prolongation

Adverse Reactions

Serious

• Anticholinergic toxicity
• CNS depression
• Seizures
• Torsades de pointes

Common

• Sedation
• Dizziness
• Headache

Pharmacology

• Half-life: Children 7 hours, Adults 3-20 hours, Elderly >20 hours
• Metabolism: Hepatic, CYP450
• Excretion: Urine
• Mechanism of Action: Nonselective antagonism of central/peripheral H1 receptors

See Also

• Antihistamines
• Anticholinergic toxicity