Methotrexate and Arava are in the same class/family of drugs. I lost my hair on methotrexate, but not as much on Arava. I had a lot of lung problems on mtx as well - not on arava.
I have a super-sensitive immune system. It seems to shut down with a lot of the drugs that are out there. While on mtx (after a year), I became very ill with a toxic liver and enlarged spleen...I was diagnosed with Epstein Barry Virus/acute mono, and it's is debatable on how much the drug had a hand in that. I did better on Arava for a while, but eventually started having high blood pressure, it came on slowly and after being on the med for a while. My weight was slowly going up as well, and everyone believed that was the BP issue, not the meds....but I have a naturally low BP and this one kept going up. Eventually, I took matters in to my own hands and stopped the meds after extensive internet research. I started to feel/see improvements within a week.
Don't let that scare you....like I said, I have a super=sensitive immune system apparently and seem to react differently than many people to meds (case in point....I take Plaquenil and it works pretty well...the Dr.s seems surprised at this). No one believed Arava could cause high blood pressure...my first round of research didn't find anything, then a few months later I did it again and found info on it right away.
Good luck! Remember to drink lots of water daily!