I've been on MTX since the middle of February, I take 3 (2.5mg) tabs every Friday. I already take 3mg of folic acid daily for mouth sores but I usually take an extra one the day I take MTX. I have tolerated it very well and it took about 6 weeks for me to see a difference in my joint pain. Be sure to tell her to take it with food, my doctor told me to take it with a large meal, not just a piece of toast or bowl of cereal. I hope it works well for your sister, let us know how she is doing.
Trust in the Lord with all thine heart, and lean not unto thine own understanding ~ Proverbs 3:5 ~
DX: Hashimoto's, Celiac Disease, Raynaud's, Lupus and Sjogrens
RX: Imuran, Plaquenil, Methotrexate, Flexeril, Piroxicam, Levoxyl, Folic Acid, Lortab (as needed) and magic mouthwash (for mouth sores)