What is the recommended dose of acyclovir (antiviral medication) for treating pityriasis rosea?

Acyclovir Dosing for Pityriasis Rosea

For pityriasis rosea requiring active treatment, use acyclovir 400 mg orally three times daily for 7 days, as this represents the most effective intervention for reducing rash severity and duration. 1, 2

When to Treat

• Most cases of pityriasis rosea are self-limiting and resolve within 6-8 weeks, requiring only reassurance and symptomatic management 3
• Active intervention with acyclovir should be considered for patients with extensive or persistent lesions, severe symptoms, or significant impact on quality of life 1, 3
• Pregnant women with pityriasis rosea may also warrant active treatment 3

Recommended Dosing Regimen

The evidence-based dosing for pityriasis rosea is:

• Acyclovir 400 mg orally three times daily for 7 days 2, 4

This regimen has been validated in multiple randomized controlled trials and demonstrates:

• Significantly fewer new lesions compared to supportive care alone 2
• Significant reduction in lesional severity by week 2 (versus week 3 with supportive care alone) 2
• Superior efficacy compared to erythromycin at all time points (weeks 1,2,4, and 6) 4
• Complete resolution in all treated patients by 8 weeks 4

Supporting Evidence Quality

• A 2024 network meta-analysis found acyclovir outperformed all other tested interventions for rash improvement (RR 2.55 vs placebo, 95% CI 1.81-3.58), ranking as the best intervention with a SUCRA score of 0.92 1
• Multiple randomized controlled trials confirm rapid clinical response, with 53% showing complete resolution by day 7 and 87% by day 14 5
• The antiviral mechanism is supported by the association of pityriasis rosea with human herpesvirus 6 and 7 reactivation 3, 2

Important Clinical Caveats

• Do not confuse this dosing with herpes simplex treatment regimens - the standard herpes labialis doses (200 mg five times daily, 400 mg three times daily for 5 days, or 800 mg twice daily for 5 days) are for different indications 6, 7
• The 7-day treatment duration for pityriasis rosea is shorter than the typical 10-day course used for herpes esophagitis 8
• Minor adverse effects may occur but are generally well-tolerated 2
• Acyclovir does not prevent recurrence of pityriasis rosea, though recurrence is rare 6

Adjunctive Symptomatic Management

• For pruritus control, oral steroids with or without antihistamines ranked highest (SUCRA 0.90), though acyclovir remains superior for overall disease resolution 1
• Standard supportive care includes cetirizine 10 mg daily and topical calamine 2