Methotrexate in pediatric dermatology: an old acquaintance, new certainties

Methotrexate (MTX) is a folic acid antagonist with antiproliferative, anti-inflammatory, and immunosuppressive effects, widely used in pediatric dermatology for the management of inflammatory and immune-mediated diseases. The objective of this review is to establish, based on current evidence, the status and utility of methotrexate in pediatric dermatology. A narrative literature review was conducted using electronic databases PubMed, Scopus, and SciELO, covering articles published in English and Spanish between 2000 and 2025. The search included the keyword “methotrexate” combined with “pediatric dermatology,” “psoriasis,” “atopic dermatitis,” “morphea,” and “alopecia areata,” as well as terms related to its “history” and “pharmacokinetics.” Clinical studies, systematic reviews, clinical practice guidelines, and relevant case series were included. Duplicate articles, studies conducted exclusively in adult populations, and those without full-text access were excluded. At low doses, MTX has demonstrated efficacy and safety in conditions such as psoriasis, severe atopic dermatitis, morphea, and alopecia areata, positioning it as a first-line therapeutic option. It is primarily administered orally at doses ranging from 0.2 to 1 mg/kg/week and requires regular monitoring with complete blood count and liver and renal function tests to prevent complications. Folic acid supplementation has been shown to reduce the frequency and severity of adverse effects, particularly gastrointestinal and hematologic events. Although the use of biologic therapies has increased over the past decade, MTX remains an accessible, cost-effective treatment with strong clinical support in the pediatric population.