What is the dosage of Atarax (hydroxyzine) for anxiety relief on an as-needed basis (PRN)?

Hydroxyzine (Atarax) PRN Dosing for Anxiety

For PRN (as-needed) anxiety relief in adults, hydroxyzine 50-100 mg orally every 6 hours as needed is the FDA-approved dosing regimen, though the evidence base for hydroxyzine is limited and benzodiazepines like lorazepam 0.5-1 mg are more strongly supported by current guidelines for acute anxiety management. 1

FDA-Approved Dosing

The FDA label specifies hydroxyzine 50-100 mg four times daily (q.i.d.) for symptomatic relief of anxiety and tension associated with psychoneurosis. 1 This translates to dosing every 6 hours when used on a scheduled basis, which can be adapted for PRN use.

• Starting dose: 50 mg orally as needed 1
• Range: 50-100 mg per dose 1
• Frequency: Can be given up to four times daily (every 6 hours) 1
• Maximum daily dose: 400 mg (100 mg × 4 doses) 1

Important Clinical Considerations

Dosage Adjustment

• The FDA emphasizes adjusting dosage according to individual patient response to therapy. 1
• Optimal assessment of response occurs after 1 week of scheduled dosing rather than PRN use, which may make titration more challenging. 2

Onset and Duration

• Hydroxyzine demonstrates anxiolytic efficacy from the first week of treatment, with early improvement in cognitive components of anxiety. 3
• The most common side effect is transient sleepiness (28-36% of patients), which typically appears during the first week and progressively diminishes with continued use. 3, 4

Comparison to Guideline-Recommended Alternatives

Current NICE guidelines recommend benzodiazepines as first-line pharmacological treatment for acute anxiety, specifically lorazepam 0.5-1 mg orally up to four times daily as needed (maximum 4 mg in 24 hours). 5 This represents a more evidence-based approach for PRN anxiety management than hydroxyzine.

• For elderly or debilitated patients, benzodiazepine doses should be reduced to 0.25-0.5 mg (maximum 2 mg in 24 hours). 5

Evidence Quality and Limitations

While hydroxyzine shows superiority over placebo for generalized anxiety disorder, a Cochrane systematic review concluded it cannot be recommended as a reliable first-line treatment due to high risk of bias in available studies, small sample sizes, and limited number of trials. 6

• Hydroxyzine at 50 mg/day produces statistically significant anxiolytic effects maintained throughout 4 weeks without rebound anxiety or withdrawal symptoms upon abrupt discontinuation. 3
• Compared to benzodiazepines (chlordiazepoxide) and buspirone, hydroxyzine showed equivalent efficacy but was associated with higher rates of sleepiness/drowsiness. 6

Common Side Effects to Counsel Patients About

• Sleepiness/drowsiness (28-36%) - typically transient 3, 4
• Dry mouth (14%) 3
• Weight gain (12%) 3
• Weakness (18%) 4
• Loss of concentration (9%) 3

Key Clinical Pitfalls

Avoid using hydroxyzine as a first-line agent when benzodiazepines are appropriate and not contraindicated, as benzodiazepines have stronger guideline support for acute anxiety management. 5, 2 However, hydroxyzine may be preferred in patients with substance use concerns given its lack of dependency potential. 7

Warn patients about first-week sedation, which can impair driving and operating machinery, though this effect typically diminishes with continued use. 3, 4