What is the recommended dosage of hydroxyzine (antihistamine) for itching?

Hydroxyzine Dosing for Pruritus

For adults with pruritus, the recommended dose is 25 mg three to four times daily (or 25-50 mg at bedtime), with the FDA-approved range being 25 mg TID or QID for histamine-mediated pruritus. 1

Standard Adult Dosing

• The FDA label specifies 25 mg three or four times daily for management of pruritus due to allergic conditions such as chronic urticaria, atopic dermatitis, and contact dermatoses 1
• For nighttime symptom control, 25-50 mg at bedtime is beneficial due to hydroxyzine's sedative properties, which can improve sleep disrupted by itching 2
• The British Association of Dermatologists recommends 10-50 mg at bedtime as a sedating antihistamine, particularly when used as an adjunct to non-sedating antihistamines during the day 3, 4

Dosing Strategy by Severity

For mild or localized pruritus:

• Begin with topical treatments and add hydroxyzine 25 mg at bedtime if nighttime symptoms are problematic 2

For moderate pruritus:

• Consider a non-sedating antihistamine (such as fexofenadine 180 mg or loratadine 10 mg) during the day with hydroxyzine 10-50 mg at night 3, 2
• This combination approach avoids daytime sedation while providing nighttime relief 4

For severe or widespread pruritus:

• Consider combination therapy with H2 antihistamines (such as cimetidine 200 mg four times daily) added to hydroxyzine 2, 5
• For refractory cases, hydroxyzine 10-25 mg QID or at bedtime can be combined with topical corticosteroids 4

Special Population Adjustments

Renal impairment:

• The dose should be halved in patients with moderate renal impairment (creatinine clearance 10-20 mL/min) 3, 2, 4

Hepatic impairment:

• Hydroxyzine should be avoided in severe liver disease due to its sedating effects 3, 2, 4

Elderly patients:

• Sedative antihistamines like hydroxyzine should not be prescribed for pruritus in elderly skin 3
• Lower dosages should be considered due to increased risk of sedative effects and anticholinergic side effects 4
• Older adults are at high risk for side effects, particularly with pre-existing conditions like prostatic hypertrophy, elevated intraocular pressure, or cognitive impairment 4

Pediatric Dosing

Children under 6 years:

• 50 mg daily in divided doses 1

Children over 6 years:

• 50-100 mg daily in divided doses 1

Important Clinical Considerations

Timing strategy:

• Bedtime dosing of hydroxyzine maintains skin H1-receptor antagonism the following morning while alleviating the psychomotor performance degradation seen with divided daytime doses 6
• This dosing strategy minimizes reaction time impairment while maintaining antipruritic efficacy 6

Duration of use:

• Sedative antihistamines are recommended in generalized pruritus of unknown origin only in the short-term or palliative setting 3
• The British Association of Dermatologists advises against extended monotherapy with hydroxyzine, favoring its use as a nighttime adjunct 4
• For mild to moderate itching, hydroxyzine can be used for 2-4 weeks 4

Contraindications:

• Hydroxyzine is contraindicated during early pregnancy according to UK manufacturer's guidelines 2, 4
• Avoid concomitant use with other CNS depressants, as this enhances performance impairment and sedation 4
• Hydroxyzine causes 80% sedation rates compared to 50% with diphenhydramine 4

Common pitfalls to avoid:

• Do not use hydroxyzine as first-line monotherapy for daytime pruritus due to sedation risk 3
• Avoid prolonged use as monotherapy due to concerns about reduced concentration and performance 4
• Do not prescribe to elderly patients with cognitive impairment or those at risk for falls 3, 4