Treatment of Linear Erythematous Pruritic Axillary Rash

Diagnostic Considerations

The American College of Physicians recommends determining if a linear pattern represents Lyme disease, which requires immediate antibiotic therapy, versus a drug-induced or inflammatory dermatosis that requires topical corticosteroids and antihistamines, with erythema migrans typically appearing 7-14 days after tick bite and should be ≥5 cm in diameter 1
The Infectious Diseases Society of America suggests reviewing all current medications, particularly immune checkpoint inhibitors, EGFR inhibitors, or other targeted cancer therapies that commonly cause pruritic rashes, and ruling out secondary bacterial infection, herpes simplex, or dermatophyte infection 2, 3

The American Academy of Dermatology recommends treating erythema migrans immediately with oral antibiotics based on clinical diagnosis without waiting for serologic confirmation, as serology is too insensitive in the first 2 weeks of infection, and diagnosis is made by visual inspection in patients with compatible epidemiologic history 1
The National Comprehensive Cancer Network suggests continuing any causative medications and applying moderate-to-high potency topical corticosteroids for Grade 1 rash, and considering holding causative medication and monitoring weekly for Grade 2 rash 2, 4
The European Society for Medical Oncology recommends initiating oral prednisone 1 mg/kg daily, tapering over at least 4 weeks, and applying high-potency topical corticosteroids for Grade 3 rash 2, 4

The American Academy of Dermatology suggests adding loratadine 10 mg once daily as first-line oral antihistamine for daytime pruritus, and using hydroxyzine 25-50 mg at bedtime or diphenhydramine 25-50 mg at bedtime for nighttime pruritus 4, 6
The National Comprehensive Cancer Network recommends adding second-line therapy with pregabalin 25-150 mg daily or gabapentin 900-3600 mg daily if antihistamines fail 4, 5

The American Academy of Dermatology suggests limiting clobetasol propionate use to 2-4 weeks maximum in the axilla, then reevaluating, due to the risk of skin atrophy 5
The European Society for Medical Oncology recommends eliminating potential contactants, including fragranced products, as the axilla is a common site for contact dermatitis from deodorants, fragrances, and preservatives 3, 5