What is the recommended dose of hydroxyzine (antihistamine) for treating allergies?

Hydroxyzine Dosing for Allergies

For allergic conditions including chronic urticaria and pruritus, the FDA-approved dose of hydroxyzine is 25 mg three to four times daily in adults, with a total daily dose of 50-100 mg in divided doses for children over 6 years. 1

Adult Dosing

• Standard dose: 25 mg three to four times daily (TID or QID) for management of pruritus due to allergic conditions such as chronic urticaria, atopic dermatitis, and contact dermatoses 1

• Alternative nighttime dosing: 10-50 mg at bedtime can be used as an adjunct to non-sedating antihistamines taken during the day, particularly beneficial for patients with sleep disruption from pruritus 2, 3

• Bedtime dosing strategy (50 mg at night) maintains effective histamine receptor blockade the following morning while mitigating the psychomotor impairment and drowsiness seen with divided daytime dosing 4

Pediatric Dosing

• Children under 6 years: 50 mg total daily dose in divided doses 1

• Children over 6 years: 50-100 mg total daily dose in divided doses 1

• Adjust dosing according to the patient's response to therapy 1

Dose Adjustments for Special Populations

Renal Impairment

• Moderate renal impairment (creatinine clearance 10-20 mL/min): Reduce dose by 50% 2, 3

• Severe renal impairment (creatinine clearance <10 mL/min): Avoid hydroxyzine 2

Hepatic Impairment

• Severe liver disease: Avoid hydroxyzine due to enhanced sedating effects 2, 3

Elderly Patients

• Use lower dosages due to increased risk of sedative effects and anticholinergic side effects 3

• Older adults are at particularly high risk for adverse effects, especially those with prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment 3

Clinical Considerations

Efficacy Profile

• Hydroxyzine demonstrates superior suppression of histamine-induced skin reactions compared to second-generation antihistamines, with over 50% of patients showing complete suppression versus only 10-20% with newer agents 5

• When standard doses of non-sedating antihistamines fail to control urticaria, adding hydroxyzine at night to the regimen can provide better symptom control 2

Sedation Management

• Hydroxyzine causes sedation in approximately 80% of patients, significantly higher than diphenhydramine (50%) or promethazine (60-73%) 3

• Evening dosing substantially reduces objective psychomotor impairment while maintaining antihistaminic efficacy 4

• Avoid concomitant use with other CNS depressants as this markedly enhances performance impairment and sedation 2, 3

Duration of Therapy

• For mild to moderate pruritus: 2-4 weeks is a reasonable treatment duration 3

• Avoid extended monotherapy with hydroxyzine; favor its use as a nighttime adjunct to non-sedating antihistamines for long-term management 3

• Transition to non-sedating antihistamines for chronic maintenance therapy 3

Important Contraindications

• Early pregnancy: Hydroxyzine is contraindicated 2, 3

• If antihistamine therapy is necessary during pregnancy, chlorphenamine is preferred due to its established safety record 2

Combination Therapy

• For refractory urticaria: Add an H2-antagonist (such as cimetidine or ranitidine) to hydroxyzine for improved symptom control 2

• This dual H1/H2 blockade approach can be particularly effective when hydroxyzine monotherapy provides inadequate relief 2