What is a recommended prn (as needed) medication for itch in eczema herpeticum?

PRN Medication for Itch in Eczema Herpeticum

Sedating antihistamines are the recommended PRN medication for itch in eczema herpeticum, with hydroxyzine being particularly effective at doses of 25 mg three to four times daily for adults. 1, 2

First-Line PRN Treatment for Itch

• Sedating antihistamines provide the most effective symptomatic relief for pruritus in eczema herpeticum due to their sedative properties 1
• Hydroxyzine is FDA-approved for management of pruritus at doses of 25 mg three to four times daily for adults 2
• Chlorphenamine (chlorpheniramine) 4-12 mg at night can be an alternative option 1
• Non-sedating antihistamines have little to no value in controlling itch in atopic eczema and are not recommended as routine treatment 1

Dosing Considerations

• For children under 6 years: hydroxyzine 50 mg daily in divided doses 2
• For children over 6 years: hydroxyzine 50-100 mg daily in divided doses 2
• Sedating antihistamines should primarily be used at night to avoid daytime sedation 1
• Large doses of antihistamines may be required in children with severe itch 1

Additional Topical Options

• Cooling antipruritic lotions such as calamine or 1% menthol in aqueous cream can provide soothing relief as adjunctive therapy 1
• Ichthammol (1% in zinc ointment) may be useful for lichenified areas 1
• Coal tar solution (1%) can be considered but should be used cautiously 1

Important Clinical Considerations

• The primary treatment for eczema herpeticum is systemic antiviral therapy (acyclovir), which should be given early in the course of disease 1, 3
• In ill, febrile patients, acyclovir should be administered intravenously rather than orally 1, 3
• Systemic antibiotics should only be added when there is clinical evidence of bacterial superinfection 1, 3
• Flucloxacillin is typically the first-line antibiotic for treating Staphylococcus aureus, the most common bacterial pathogen in superinfected eczema herpeticum 1, 3

Cautions and Contraindications

• Hydroxyzine is contraindicated during early pregnancy 1
• In patients with hepatic impairment, avoid chlorphenamine and hydroxyzine in severe liver disease 1
• For patients with renal impairment, the dose of hydroxyzine should be halved 1
• Tachyphylaxis may develop with prolonged use of antihistamines, reducing their effectiveness over time 1

Monitoring and Follow-up

• Assess response to antihistamine therapy within 48-72 hours
• If inadequate response to one sedating antihistamine, consider switching to another as individual responses vary 1
• Monitor for excessive sedation, especially in patients taking other CNS depressants
• Ensure that the underlying eczema herpeticum is being appropriately treated with antiviral therapy 3