There is evidence to suggest that children diagnosed with ADHD who do not receive treatment will have an increased risk of substance use disorders as adults.The precise magnitude of improvement in ADHD symptoms and quality of life that are produced by methylphenidate treatment remains uncertain as of November 2015. Methylphenidate is not included in the World Health Organization Essential Medicines List, as findings by the World Health Organization indicate that evidence of benefit versus harm to be unclear in the treatment of ADHD. A 2021 systematic review concluded that there is no clear evidence for using IR Methylphenidate (immediate-release) for adults.Since ADHD diagnosis has increased around the world, methylphenidate may be misused as a "study drug" by some populations, which may be harmful. This also applies to people who may be experiencing a different issue and are misdiagnosed with ADHD. People in this category can then experience negative side-effects of the drug which worsen their condition. Narcolepsy
Narcolepsy, a chronic sleep disorder characterized by overwhelming daytime drowsiness and uncontrollable sleep, is treated primarily with stimulants. Methylphenidate is considered effective in increasing wakefulness, vigilance, and performance. Methylphenidate improves measures of somnolence on standardized tests, such as the Multiple Sleep Latency Test (MSLT), but performance does not improve to levels comparable to healthy people. Other medical uses
Methylphenidate may also be prescribed for off-label use in treatment-resistant cases of bipolar disorder and major depressive disorder. It can also improve depression in several groups including stroke, cancer, and HIV-positive patients.
Unlawful possession is punishable by six-month prison sentence and distribution by a 14-year sentence. In Australia, methylphenidate is a Schedule 8 controlled substance. Such drugs must be kept in a lockable safe until dispensed and possession without prescription is punishable by fines and imprisonment. In Russia, methylphenidate is a List I controlled psychotropic substance without recognized medical value. The Constant Committee for Drug Control of the Russian Ministry of Health has put methylphenidate and its derivatives on the National List of Narcotics, Psychotropic Substances and Their Precursors and the Government banned methylphenidate for any use on 25 October 2014. In Sweden, methylphenidate is a List II controlled substance with recognized medical value. Possession without a prescription is punishable by up to three years in prison. In France, methylphenidate is covered by the "narcotics" schedule, prescription and distribution conditions are restricted with hospital-only prescription for the initial treatment and yearly consultations. In India, methylphenidate is a schedule X drug and is controlled by the Drugs and Cosmetics Rule, 1945. It is dispensed only by physicians prescription. Legally, 2 grams of methylphenidate are classified as a small quantity, and 50 grams as a large or commercial quantity. In Hong Kong, methylphenidate is controlled under the schedule 1 of the Dangerous Drugs Ordinance (Cap. 134). Controversy
Methylphenidate has been the subject of controversy in relation to its use in the treatment of ADHD. The prescription of psychostimulant medication to children to reduce ADHD symptoms has been a major point of criticism.