What is the recommended dosing for Atarax (hydroxyzine) as needed (prn)?

Atarax (Hydroxyzine) PRN Dosing

For anxiety and agitation, start with hydroxyzine 25-50 mg PO every 4-6 hours as needed, with a maximum of 100 mg per dose in adults; for pruritus, use 25 mg PO three to four times daily as needed. 1

Standard PRN Dosing by Indication

Anxiety and Agitation

• Adults: 50-100 mg PO every 4-6 hours as needed 1
• Starting dose: Begin with 25-50 mg to assess tolerance, particularly in elderly or frail patients
• Maximum single dose: 100 mg 1
• The FDA label specifies dosing for "symptomatic relief of anxiety and tension associated with psychoneurosis" at 50-100 mg four times daily 1

Pruritus (Allergic Conditions)

• Adults: 25 mg PO three to four times daily as needed 1
• This lower dose is specifically for histamine-mediated pruritus, chronic urticaria, and contact dermatoses 1

Preoperative Sedation

• Adults: 50-100 mg as a single dose 1
• Administered as premedication before procedures or following general anesthesia 1

Pediatric PRN Dosing

• Children under 6 years: 50 mg daily in divided doses (for both anxiety and pruritus) 1
• Children over 6 years: 50-100 mg daily in divided doses 1
• Preoperative sedation: 0.6 mg/kg of body weight 1

Clinical Context and Positioning

Comparison to Other Agents for Acute Agitation

While hydroxyzine can be used for anxiety and agitation, lorazepam 1-2 mg is the preferred first-line PRN agent for acute undifferentiated agitation due to its rapid onset and favorable safety profile 2. Hydroxyzine is not mentioned in current acute agitation guidelines, suggesting it is better suited for chronic anxiety management or pruritus rather than acute behavioral emergencies 2.

Evidence for Efficacy

• Hydroxyzine demonstrated superiority over placebo for generalized anxiety disorder (OR 0.30,95% CI 0.15 to 0.58), though the evidence quality was limited by high risk of bias 3
• In a clinical study of 55 patients with anxiety disorders, hydroxyzine 50 mg daily for 28 days showed significant reduction in Hamilton Anxiety Scale scores, particularly for somatic anxiety symptoms 4
• Recent evidence suggests hydroxyzine may have a role in delirium management, with one study showing a delirium improvement rate of 23.9% versus 8.5% for haloperidol 5

Key Safety Considerations

Sedation Profile

• Primary side effect: Drowsiness/sleepiness is the most common adverse effect 3
• Hydroxyzine has sedating and anticholinergic properties that may be beneficial for anxiety with insomnia but problematic for daytime functioning 6
• Patients should be counseled about impaired alertness and avoiding activities requiring mental acuity 1

Dosing Adjustments

• Elderly patients: Start with lower doses (25 mg) and titrate gradually due to increased sensitivity to anticholinergic effects and sedation
• Hepatic impairment: Reduce doses as hydroxyzine undergoes hepatic metabolism 1
• The FDA label emphasizes that "dosage should be adjusted according to the patient's response to therapy" 1

Route of Administration

• Oral only for PRN use: Hydroxyzine is available in oral formulations (tablets, capsules, syrup) 1
• While IM formulations exist, the FDA label specifies that "when treatment is initiated by the intramuscular route, subsequent doses may be administered orally" 1
• This oral-only limitation makes hydroxyzine less suitable for severely agitated or uncooperative patients who cannot take oral medications 2

Common Pitfalls

• Avoid in acute severe agitation: Hydroxyzine's slower onset compared to benzodiazepines or antipsychotics makes it inappropriate for emergency behavioral control 2
• Anticholinergic burden: Be cautious in elderly patients or those on other anticholinergic medications due to risk of confusion, urinary retention, and constipation
• Not a substitute for scheduled therapy: PRN hydroxyzine should not replace optimization of scheduled anxiety medications or addressing underlying causes of agitation