Maximum Daily Vistaril (Hydroxyzine) Dose
The maximum daily dose of Vistaril (hydroxyzine) for adults is 400 mg per day, administered as 100 mg four times daily for anxiety and tension. 1
FDA-Approved Dosing by Indication
According to the FDA drug label, hydroxyzine dosing varies by indication 1:
For Anxiety and Tension (Psychoneurosis)
- Adults: 50-100 mg four times daily (maximum 400 mg/day)
- This represents the highest approved daily dose
For Pruritus (Allergic Conditions, Chronic Urticaria)
- Adults: 25 mg three to four times daily (maximum 100 mg/day)
- Significantly lower than anxiety dosing
For Sedation (Premedication/Post-Anesthesia)
- Adults: 50-100 mg as single doses
Clinical Context from Guidelines
The British Journal of Dermatology urticaria guidelines 2 consistently reference hydroxyzine at 10-50 mg at night when used as adjunctive therapy to nonsedating antihistamines. This is substantially below the FDA maximum and reflects real-world practice patterns where:
- Hydroxyzine is typically reserved for nighttime use due to sedation
- The standard dose of 25 mg four times daily (100 mg/day) from the rhinitis guideline table 3 represents typical clinical practice
- Higher doses (up to 400 mg/day) are reserved for psychiatric indications
Important Dosing Modifications
Renal Impairment
The dose must be halved in patients with renal impairment 2. This is critical as hydroxyzine is renally cleared.
Hepatic Impairment
Hydroxyzine should be avoided in severe liver disease due to inappropriate sedating effects 2.
Critical Safety Considerations
- Sedation is the predominant effect: 80% sedation rate reported 3, making doses above 100 mg/day impractical for most outpatients
- Anticholinergic burden: Particularly problematic in elderly patients with prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment 3
- Recent research shows hydroxyzine causes less antimuscarinic toxicity than diphenhydramine in overdose 4, but daytime somnolence remains significant 5
Practical Recommendation
While the FDA maximum is 400 mg/day for psychiatric indications, most patients should not exceed 100 mg/day (25 mg four times daily) in routine practice. For urticaria or pruritus specifically, stay at or below 100 mg/day as per FDA labeling 1. The 400 mg/day maximum is reserved for anxiety disorders under psychiatric supervision where the sedation can be monitored and tolerated.