I have adhd, i'm 20 years old. im medicated, currently studying medicine. how will it affect my future and my career? and long term use of ritalin (methylphenidate)?

Congratulations!: As long as you are focused on pursuing a career in medicine for the right reasons, you'll be doing well! To answer your question, Ritalin (methylphenidate) has been used for ADHD for more than 50 years, and there have not been any well documented long term adverse effects for long term use. The positive effect is it allows you to do well enough to want to study medicine! You take is as long as it helps you function.

Stimulants lifelong: Stimulant medications are effective treatment for ADHD. Generally well tolerated, they do have a downside. Problems with appetite suppression and rebound gorging may occur. Rebound irritability and ADHD symptoms may occur when the medication wears off. They have been found to be remarkably safe since their first use in 1934. If rebound side effects are an issue, consider the pro-drug, Vyvanse (lisdexamfetamine).