The present invention relates to methotrexate, a pharmaceutically acceptable salt thereof, or a hydrate thereof, for use as a medicament, characterized in that methotrexate, a pharmaceutically acceptable salt, or a hydrate thereof is administered at a dose which is decreased within a treatment time comprising at least two subsequent sequential time periods in the form of a first and a second time period, each time period comprising at least one week, wherein the dose administered in the second time period is lower than that of the first time period, with the proviso that within the total treatment time, the average dose of methotrexate, a pharmaceutically acceptable salt there of, or a hydrate thereof administered is at least 20 mg/week.