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[B] The following conclusions are supported by fair evidence:
Methotrexate, and to a lesser extent the long-term use of non-steroidal anti-inflammatory (NSAIDs) medications, such as aspirin, may cause folic acid deficiency. Serum levels should be monitored closely in all individuals on this medication, and especially in women of childbearing age. Supplementation of 5-10 mg of folic acid once weekly by mouth after taking the methotrexate dose is recommended to help prevent
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