My mom is on Enbrel. She began in May of 2009. Prior to that she was on Arava for five months and it almost killed her. She lost 60 lbs, had heart issues, urinary tract infections, had no appetite and was incredibly weak. Her RA doctor said it was not the Arava. It was. I took her to the Lahey Cllinic and they confirmed it. I had taken her off the medication before going to the Lahey Clinic but it was a binding med. so it stayed in her system for months afterwards.
I'm writing this because if you feel a medication is having an effect on you, listen to your body. These doctors go by the textbook and as humans we are all different.
I have the same concern.. I've been on a generic - Levothyroxine - for ~9 years and have developed a head tremor over the course of the last 2. It's the same sort of tremor my mother has. She was diagnosed and treated 30 years ago and has taken the same generic for 15. My sister has been taking the same thing for as long as I have, but has no tremor.
I've been on Enbrel for almost 9 years. I've recently been developing tremors in my hands, cheeks (when I smile), and tongue. Talked to my rheumy. He doesn't think it's the Enbrel, but I am growing more concerned. They're not bad, but they do seem to be progressing.