Methotrexate
"Started mtx in early 2010, I was on it the better part of the last 5  years.  I'm also on my fourth biologic.  I take 2mg of folic acid daily.  Last May I did a four day stretch in hospital because of bone marrow suppression.  RBC, WBC, ANC, platelets and hemoglobin were very low.  (ANC under 200).  I was given leucorvorin rescue.  This is a very rare side effect for low dose mtx.  Although the drug only gave me a 10 to 20% improvement, the biologic gives me 60 to 90%.  Now I'm about to start Arava, I wish I could retry the mtx at half dose as it doesn't cause much in the way of minor side effects.  I often think of Huey Lewis and his song "I want a new drug"."