How long have you been taking the ritalin? What doses have you tried? Did the Dr. start small and ramp you up or just start at 40mg? Im also assuming this is extended release as 40mg instant release is high, espicially to start out with. There is no right dosage. everyone is different. The side effects wear off as your body gets used to the drug. I was taking concerta(same drug, different name and release form) and after a few months i was sure i wanted to try soomething else. I tried adderall and have been a happy camper since.
www.addforums.com is an excellent source of info.