The wide variety of methotrexate dosing regimens for the treatment of atopic dermatitis: a systematic review

Background: Methotrexate is an off-label therapy for atopic dermatitis. A lack of consensus on dosing regimens poses a risk of underdosing and ineffective treatment or overdosing and increased risk of side effects. This systematic review summarizes the available evidence on dosing regimens. Materials and methods: A literature search was conducted, screening all randomized controlled trials (RCTs) and guidelines published up to 6 July 2023, in the MEDLINE, Embase, and Cochrane Library databases. Results: Five RCTs and 21 guidelines were included. RCTs compared methotrexate with other treatments rather than different methotrexate dosing regimens. The start and maintenance doses in RCTs varied between 7.5–15 mg/week and 14.5–25 mg/week, respectively. Despite varied dosing, all RCTs demonstrated efficacy in improving atopic dermatitis signs and symptoms. Guidelines exhibited substantial heterogeneity but predominantly proposed starting doses of 5–15 mg/week for adults and 10–15 mg/m2/week for children. Maintenance doses suggested were 7.5–25 mg/week for adults and 0.2–0.7 mg/kg/week for children. One guideline suggested a test dose and nearly half advised folic acid supplementation. Conclusion: This systematic review highlights the lack of methotrexate dosing guidelines for atopic dermatitis. It identifies commonly recommended and utilized dosing regimens, serving as a valuable resource for clinicians prescribing methotrexate off-label and providing input for an upcoming consensus study.