To report previously underrecognized postdosing side effects of methotrexate (MTX).
Over a one and a half year period, in 2 practices, all patients with rheumatoid arthritis (RA) receiving weekly MTX, and volunteering symptoms within a few hours of MTX dosing were carefully questioned concerning the nature of the postdosing reaction.
Of 356 patients, 36 (10%) reported a previously underemphasized postdosing reaction consisting of arthralgias/myalgias, fatigue/malaise or both. Sixteen patients discontinued MTX primarily because of this side effect.
In these patient populations, postdosing reactions were the 2nd most common side effect (after gastrointestinal) leading to MTX withdrawal.