What is the role of hydroxyzine in treating itching?

Hydroxyzine for Itching

Hydroxyzine is an effective first-generation antihistamine for treating pruritus, particularly useful for nighttime dosing due to its sedative properties (25-50 mg daily), while non-sedating second-generation antihistamines are preferred for daytime use. 1

Mechanism of Action

• Hydroxyzine acts as a potent H1-receptor antagonist with sedative properties, suppressing activity in key regions of the subcortical central nervous system 2
• Clinical effects typically begin within 15-30 minutes after oral administration 2
• Beyond antihistamine effects, hydroxyzine demonstrates bronchodilator activity, analgesic effects, and mild antisecretory activity 2

Clinical Applications

Mild to Moderate Pruritus (Grade 1)

• Hydroxyzine can be used alongside topical moderate/high-potency steroids 1
• Typical dosing is 10-25 mg QID or at bedtime for mild localized pruritus 1
• Can be combined with non-sedating antihistamines (cetirizine/loratadine) for 24-hour coverage 1

Moderate to Severe Pruritus (Grade 2)

• For intense or widespread pruritus with intermittent symptoms, hydroxyzine remains a viable option 1
• Often used in combination with topical steroids and/or GABA agonists (pregabalin/gabapentin) 1
• Dosing may be increased to 25-50 mg daily, particularly at night 1

Severe Pruritus (Grade 3)

• For intense, widespread, and constant pruritus limiting self-care activities, hydroxyzine can be part of a multimodal approach 1
• May need to be combined with oral corticosteroids (0.5-1 mg/kg/day of prednisone) for temporary relief of severe symptoms 1
• In cases of treatment failure, consider GABA agonists or specialist referral 1

Dosing Considerations

• For nighttime pruritus: 25-50 mg at bedtime to leverage sedative properties 1
• For daytime coverage: Consider non-sedating antihistamines instead (loratadine 10 mg daily) 1
• In renal impairment: Dose should be halved in moderate renal impairment and avoided in severe renal impairment 1
• In hepatic impairment: Should be avoided in severe liver disease due to inappropriate sedating effects 1
• Contraindicated during early pregnancy 1

Efficacy Evidence

• Real-world observational data shows significant improvement in quality of life and pruritus scores over 12 weeks of hydroxyzine treatment 3
• Studies have shown hydroxyzine to be as effective as newer antihistamines for urticaria, with 47% reduction in daily symptom scores 4
• Bedtime dosing maintains skin H1-receptor antagonism through the following morning while minimizing daytime sedation 5

Adverse Effects and Limitations

• Common side effects include sedation, drowsiness, dizziness, dry mouth, and constipation 3
• Significantly higher rates of somnolence compared to non-sedating antihistamines (40% vs. 5%) 4
• Adding hydroxyzine at night to daytime non-sedating antihistamines increases daytime somnolence without improving treatment efficacy 6
• Rare cases of worsening dermatitis in patients with sensitivities to phenothiazines or ethylenediamines 7

Special Considerations

• For chronic urticaria, guidelines recommend using non-sedating second-generation antihistamines as first-line treatment 6
• When using hydroxyzine for more than 3 weeks at high doses, consider GI prophylaxis with proton pump inhibitors 1
• In cases where hydroxyzine is ineffective, consider antiepileptic agents (pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily) as second-line treatment 1
• For treatment-resistant cases, dermatology referral is recommended 1