What is the full prescription and treatment plan for Pityriasis rosea, including dosing and required tests?

Pityriasis Rosea Treatment Protocol

Pityriasis rosea is a self-limiting condition that requires no active treatment in most cases—reassurance alone is appropriate for typical presentations, but acyclovir 800 mg five times daily for 7 days is the most effective intervention when treatment is warranted for extensive, persistent, or symptomatic disease. 1

Clinical Diagnosis (No Tests Required)

• No laboratory tests or imaging are required for diagnosis—pityriasis rosea is diagnosed clinically based on the characteristic herald patch followed by a generalized eruption along Langer's lines in a "Christmas tree" pattern on the trunk 2, 3
• Consider serologic testing for syphilis (RPR or VDRL) only if the clinical presentation is atypical or if secondary syphilis cannot be excluded based on history and examination 3
• Skin biopsy is not routinely indicated unless the diagnosis is uncertain or the rash persists beyond 12 weeks 2

Treatment Algorithm

Step 1: Typical Cases (80% of patients)

• Reassurance and observation only—the condition resolves spontaneously in 6-8 weeks without intervention 2, 3, 4
• Educate patients that lesions will resolve completely without scarring in the vast majority of cases 2

Step 2: Symptomatic Treatment for Pruritus

When itching is bothersome:

• Oral antihistamines: Cetirizine 10 mg daily or loratadine 10 mg daily for itch control 3
• Topical corticosteroids: Low-to-medium potency (hydrocortisone 1% or triamcinolone 0.1% cream) applied twice daily to pruritic areas 3
• Oral corticosteroids + antihistamines: Prednisone 20-40 mg daily for 1-2 weeks combined with antihistamines is highly effective for severe pruritus (SUCRA 0.90 for itch resolution) 1

Step 3: Active Intervention for Severe/Extensive Disease

When treatment is indicated (extensive lesions, severe symptoms, or patient preference):

First-Line: Acyclovir

• Acyclovir 800 mg orally five times daily for 7 days is the most effective treatment for both rash improvement (SUCRA 0.92) and reducing disease duration 1, 3
• Start within the first week of rash onset for maximum benefit 2
• Acyclovir significantly outperforms all other interventions for rash resolution (RR 2.55,95% CI 1.81-3.58 vs placebo) 1

Alternative: Erythromycin

• Erythromycin 250-500 mg orally four times daily for 14 days is a reasonable alternative, particularly in children or pregnant women where acyclovir may be avoided 2, 1
• Less effective than acyclovir but still superior to placebo (RR 1.69,95% CI 1.23-2.33) 1

Step 4: Refractory Cases

• Ultraviolet B (UVB) phototherapy: Consider for severe, persistent cases unresponsive to oral therapy 3
• Administer narrow-band UVB three times weekly until resolution 3

Special Population: Pregnancy

• Urgent evaluation required—pityriasis rosea in pregnancy, particularly in the first 15 weeks, is associated with increased risk of spontaneous abortion and adverse fetal outcomes 3, 5
• Erythromycin 250-500 mg four times daily for 14 days is preferred over acyclovir due to better safety profile in pregnancy 2
• Close obstetric monitoring is essential 5

Common Pitfalls to Avoid

• Do not prescribe antibiotics for typical pityriasis rosea—this is a viral reactivation (HHV-6/HHV-7), not a bacterial infection; antibiotics like erythromycin work through anti-inflammatory mechanisms, not antimicrobial activity 2, 5
• Do not use prolonged or potent topical corticosteroids—these can cause skin atrophy and are unnecessary since the condition is self-limited 3
• Do not miss secondary syphilis—always consider syphilis serology if there are palmar/plantar lesions, mucosal involvement, or high-risk sexual history 3
• Do not delay treatment in pregnancy—early intervention may reduce fetal complications 5

Prescription Template for Active Treatment

For extensive/symptomatic pityriasis rosea:

• Acyclovir 800 mg PO five times daily × 7 days 1
• Cetirizine 10 mg PO daily PRN pruritus × 4-6 weeks 3
• Triamcinolone 0.1% cream, apply to pruritic areas BID PRN × 2-4 weeks 3

For pregnant patients:

• Erythromycin 500 mg PO QID × 14 days 2
• Cetirizine 10 mg PO daily PRN pruritus (Category B) 3