Two patients with serious skin diseases were treated with intermittent, intramuscularly administered methotrexate in doses of 50 to 75 mg. Fever, cough, dyspnea, and bilateral noninfectious pulmonary infiltrates developed in both patients after several weeks of therapy. The respiratory illness were attributed to a pulmonary reaction, possibly allergic in nature, produced by methotrexate. Previous instances of pulmonary infiltrates secondary to methotrexate have been reported only in leukemic patients receiving intermittent therapy.
Goldman GC, Moschella SL. Severe Pneumonitis Occurring During Methotrexate TherapyReport of Two Cases. Arch Dermatol. 1971;103(2):194-197. doi:10.1001/archderm.1971.04000140080014