What is the maximum recommended dose of Atarax (hydroxyzine) for an adult?

Maximum Dose of Hydroxyzine (Atarax) in Adults

The maximum recommended dose of hydroxyzine for adults is 100 mg four times daily (400 mg/day total) when administered intramuscularly for anxiety, though practical clinical use typically limits oral dosing to 50 mg at bedtime to minimize severe sedation and performance impairment. 1

FDA-Approved Maximum Dosing by Indication

The FDA label provides the following maximum doses for adults 1:

• Anxiety and tension (psychoneurosis): 50–100 mg four times daily (up to 400 mg/day)
• Pruritus (allergic conditions, chronic urticaria): 25 mg three to four times daily (up to 100 mg/day)
• Premedication/sedation: 50–100 mg as a single dose

Evidence-Based Practical Dosing Recommendations

For real-world clinical practice, hydroxyzine should be limited to 50 mg at bedtime when used as an adjunct to non-sedating antihistamines, rather than employing the FDA's maximum approved doses. 2 This approach minimizes the substantial risks of daytime sedation, cognitive impairment, and driving accidents while maintaining therapeutic benefit.

Why Lower Doses Are Preferred in Practice

• Hydroxyzine causes sedation in approximately 80% of patients—significantly higher than diphenhydramine (50%) or promethazine (60–73%)—making multiple daily dosing particularly hazardous 2
• Performance impairment persists even when patients deny subjective drowsiness, and drivers taking hydroxyzine are 1.5 times more likely to be responsible for fatal automobile accidents 2
• The long half-life of 20 ± 4.1 hours means bedtime dosing provides sustained effects into the next day, making multiple daily doses unnecessary and dangerous 3, 2

Critical Dose Reductions Required

Renal Impairment

• Moderate renal impairment (CrCl 10–20 mL/min): Reduce dose by 50% 3, 2
• Severe renal impairment (CrCl <10 mL/min): Avoid hydroxyzine entirely 2

Hepatic Impairment

• Severe liver disease: Absolute contraindication—avoid hydroxyzine completely due to risk of excessive sedation and hepatic encephalopathy 3, 2

Elderly Patients

• Start at the low end of the dosing range (10 mg at bedtime) due to increased risk of falls, fractures, anticholinergic effects, and cognitive impairment 2
• Hydroxyzine is specifically listed among medications that should be deprescribed in older adults due to fall risk and CNS impairment 2

Practical Dosing Algorithm for Common Indications

For Pruritus or Urticaria with Sleep Disturbance

1. First-line: Start a non-sedating antihistamine (e.g., cetirizine 10 mg or loratadine 10 mg) in the morning 2
2. If nighttime symptoms persist after 2–4 weeks: Add hydroxyzine 10–50 mg at bedtime (not as monotherapy) 2
3. Dose titration: Adjust based on tolerability, starting at 10 mg in elderly patients and halving the dose in moderate renal impairment 2
4. Avoid: Multiple daily dosing or AM/PM split dosing due to severe daytime impairment 2

For Anxiety (Off-Label Use)

• While the FDA approves up to 100 mg four times daily for anxiety 1, clinical studies support 50 mg/day as effective for generalized anxiety disorder with better tolerability 4

Common Pitfalls to Avoid

• Never use hydroxyzine as prolonged monotherapy for pruritus or urticaria—it should only be a nighttime adjunct to non-sedating antihistamines 2
• Avoid concomitant CNS depressants (benzodiazepines, opioids, alcohol) as this dramatically enhances performance impairment and sedation 2
• Do not assume tolerance develops—performance impairment can persist without subjective awareness of drowsiness 2
• Screen for anticholinergic burden—particularly dangerous in elderly patients with prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment 3, 2
• Discontinue at least 6 days before skin prick testing due to antihistaminic effects 3

Absolute Contraindications

• First trimester of pregnancy: Hydroxyzine is the only antihistamine explicitly contraindicated during early pregnancy 3, 2
• Severe hepatic disease 3, 2
• Severe renal impairment (CrCl <10 mL/min) 2
• Significant cardiac disease: Consider alternative antihistamines 3

Safety Monitoring

• Elderly patients: Mandatory medication review for CNS depressants, QT-prolonging agents, and anticholinergic drugs before initiating hydroxyzine 2
• Occupational considerations: Hydroxyzine impairs learning, work performance, and increases occupational accidents—avoid in patients requiring optimal cognitive function 2
• Driving risk: Counsel patients about 1.5-fold increased risk of fatal automobile accidents 2