Systemic Therapies: Methotrexate 

Methotrexate is used in low doses to treat severe psoriasis, atopic dermatitis, and morphea. When used at dermatologic doses (0.2-0.5mg/kg/week) the risk of side effects is low. Possible side effects can include hepatotoxicity, pulmonary toxicity, and pancytopenias. It is also teratogenic and females must not become pregnant while on methotrexate. Many patients experience some nausea and/or feel unwell the day after taking their methotrexate.  They may chose to take it on the weekend as a result. Baseline laboratory monitoring includes CBC diff, liver function tests, BUN and creatinine, hepatitis B & C and HIV screen, and a pregnancy test. Follow-up labs are CBC with differential and LFT’s weekly for 2-4 weeks and then every 3 months and after any dose escalations. Kidney function should be checked annually. Folic acid 1-5mg is to be taken daily except on days of methotrexate.