[10] In general, potential side effects include: muscle hypertrophy, acne, hypertension, elevated cholesterol, thrombosis, decreased high-density lipoproteins, altered libido, hepatic carcinoma, cholestasis, peliosis hepatitis, septic arthritis, Wilm's tumor, psychosis, aggression, addiction, and depression.
Low (therapeutic) doses of dopaminergic stimulants (e.g., reuptake inhibitors and releasing agents) also promote mental and athletic performance, as cognitive enhancers and ergogenic aids respectively, by improving muscle strength and endurance while decreasing reaction time and fatigue.
[3][14][15][18][19] Potential side effects include hypertension, insomnia, headaches, weight loss, arrhythmia, tremors, anxiety, addiction, and strokes.
[20] Some stimulants are allowed in competitive sports and are widely accessible, though may also be monitored by the World Anti-Doping Agency (WADA), such as caffeine.
[21][22] Ergogenic aids, or athletic performance-enhancing substances, include a number of drugs with various effects on physical performance.
Drugs such as amphetamine and methylphenidate increase power output at constant levels of perceived exertion and delay the onset of fatigue,[18][19][23] among other athletic-performance-enhancing effects;[3][14][15] bupropion also increases power output at constant levels of perceived exertion, but only during short-term use.
[33] As of 2008, the position of the European Medicines Agency was that "The principle of an adaptogenic action needs further clarification and studies in the pre-clinical and clinical area.
"[34] Actoprotectors or synthetic adaptogens are compounds that enhance an organism's resilience to physical stress without increasing heat output.
Painkillers used by athletes range from common over-the-counter medicines such as NSAIDs (such as ibuprofen) to powerful prescription narcotics.
[41] Potential side effects include: dehydration and an increase in blood viscosity which could result in a pulmonary embolism or stroke.
[example needed][43] Gene doping agents are a relatively recently described class of athletic performance-enhancing substances.
[47] Androstenedione in 2005 became classified as a controlled substance by WADA, however DHEA can still be obtained legally as an over-the-counter nutritional supplement.
[48] While the use of PEDs has expanded in recent times, the practice of using substances to improve performance has been around since the Ancient Olympic Games.
[49] In the Olympic Games of 668 BC, Charmis had consumed a diet consisting of dried figs which was thought, at the time, to be a significant factor in winning the 200-yard stade race.
[53] The main substances being used included alcoholic drinks, caffeine, and mixtures created by the athletic trainers (e.g., strychnine tablets made of cocaine and brandy).
[58] In 1988, the United States Congress established the Anti-Drug Abuse Act to criminalize the distribution and possession of non-medical anabolic steroids.
[60] This is in part due to the significance placed on physical appearance by this age group as well as feelings of invincibility combined with a lack of knowledge surrounding long-term consequences.
[52] Adolescents who partake in competitive sports are at a particularly high risk, with those involved in gridiron football, basketball, wrestling, baseball, and gymnastics at the top.