Maximum Daily Dose of Hydroxyzine
The maximum daily dose of hydroxyzine for adults is 400 mg per day (100 mg four times daily) when used for anxiety and tension, as specified by the FDA label. 1
Standard Dosing by Indication
The FDA-approved maximum doses vary by clinical indication 1:
- Anxiety and tension (psychoneurosis): 50-100 mg four times daily (maximum 400 mg/day) 1
- Pruritus (allergic conditions, chronic urticaria): 25 mg three to four times daily (maximum 100 mg/day) 1
- Premedication/sedation: 50-100 mg as a single dose 1
Practical Dosing Strategies
For nighttime sedation and pruritus management, 10-50 mg at bedtime is recommended as an adjunct to non-sedating antihistamines during the day. 2 This bedtime dosing strategy has been shown to maintain antihistamine efficacy while mitigating the psychomotor impairment and reaction time prolongation seen with divided daytime dosing 3.
- Hydroxyzine 50 mg at bedtime maintains histamine receptor antagonism the following morning without the significant reaction time degradation observed with divided doses 3
- For patients with urticaria not responding adequately, adding an H2-antagonist like cimetidine may provide better symptom control 4
Dose Adjustments for Special Populations
In moderate renal impairment (creatinine clearance 10-20 mL/min), reduce the dose by half. 4, 2
- Severe renal impairment (creatinine clearance <10 mL/min): Avoid hydroxyzine entirely 4
- Severe hepatic disease: Avoid due to enhanced sedating effects 4, 2
- Elderly patients: Use lower doses due to increased risk of sedative effects and anticholinergic complications, particularly in those with prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment 2
Critical Safety Considerations
Hydroxyzine produces significant CNS depression with 80% sedation rates—higher than diphenhydramine (50%) or promethazine (60-73%). 2 This creates important clinical implications:
- Avoid concomitant use with other CNS depressants, as this markedly enhances performance impairment 4, 2
- Hydroxyzine significantly prolongs both simple and choice reaction times without development of tolerance over 5 days of administration 5
- Subjective symptoms (drowsiness, dry mouth) do not reliably predict objective performance impairment, meaning patients may feel fine while still experiencing measurable cognitive deficits 5
- Recent forensic data shows hydroxyzine is now the most commonly identified antihistamine in impaired driving investigations, with drivers exhibiting incoordination, slurred speech, erratic driving, and crashes 6
Duration of Treatment
Extended monotherapy with hydroxyzine is not recommended; favor its use as a nighttime adjunct to non-sedating antihistamines for long-term management. 2
- For mild to moderate pruritus, typical treatment duration is 2-4 weeks 2
- In generalized anxiety disorder, hydroxyzine 50 mg/day demonstrated sustained efficacy over 12 weeks without rebound anxiety upon discontinuation 7
Contraindications
Hydroxyzine is contraindicated in early pregnancy. 4, 2 If antihistamine therapy is necessary during pregnancy, chlorphenamine is preferred due to its established safety record 4.