I have been on Leflunomide- 20mg- for 18mths - it was added to mtx when that did not seem to be controlling things. For me - neither did leflunomide - but my blood pressure went up - needing yet more tablets for that!!!!!!!!!!!!!
I have constantly asked, at consultants appointments, if I can stop the leflunomide but have been told not to - only this week asked again- and told 'no, because although you dont think it's helping - it might be'.
As with all of us - each drug combination affects us differently - some things work well for some and some dont. It seems it's all trial and error.
Good luck with yours.