Methylphenidate, sold under the brand name Ritalin and Concerta among others, is a stimulant drug used to treat attention deficit-hyperactivity disorder (ADHD) and narcolepsy. It is a first-line medication for ADHD. It may be taken by mouth or applied to the skin, and different formulations have varying durations of effect. It is also used recreationally as a performance-enhancer and/or as a euphoriant.
Common side effects of methylphenidate include: anxiety, paranoia, irritability, agitation, euphoria, difficulty sleeping, loss of appetite, and weight loss. More serious side effects may include addiction, dependence, substance abuse, delusions, hallucinations, psychosis, mania, panic attacks, aggression, violent behavior, seizures, and prolonged erections. Withdrawal symptoms include: dysphoria, depression, exhaustion, drowsiness, lethargy, weakness, dizziness, apathy, irritability, restlessness, headaches, chills, suicidal thoughts, and nightmares.