i have been on methotrexate 10 mgs every 3 days for treatment of servere plaque psoriasis and i require fusion for a spinal problem. this will not be done unless i stop taking the methotrexate. what i need to know is how long will it take to be completely out of my system. i have been taking it for about 3 years on this dose. My liver tests have always been good and i'm in good health.