Athletes sometimes use performance-enhancing substances to increase training adaptations and improve sport performance. In an ideal world, any substance used would also support health and follow the ethical and regulatory rules of the sport. However, concerns about unfair competitive advantages and potential adverse effects have led most governing bodies to publish lists of banned substances. Athletes who use prohibited substances may face suspension, forfeiture of medals, or lifetime bans for repeated violations.

Although many substances are prohibited, a wide range of nutritional supplements and ergogenic aids are legal and commonly used to support performance. Before using any product, athletes need to understand both its legality and its safety.

Distinction between drugs and dietary supplements

The main difference between a drug and a dietary supplement is FDA approval for safety and effectiveness. Drugs must undergo extensive testing before they can be marketed. Dietary supplements, in contrast, can be sold with minimal regulation unless a health risk is identified.

Dietary supplements may provide macronutrients, micronutrients, or bioactive compounds (such as protein, creatine, or caffeine) that can affect health or performance. Some strategies are considered part of the diet rather than supplementation. For example, carbohydrate loading before competition is a dietary strategy, whereas a carbohydrate product sold in tablet or powder form is classified as a dietary supplement.

Definition of products that can be sold as dietary supplements

Dietary supplements in the U.S. must meet the following criteria:

1. The product (excluding tobacco) must supplement the diet and contain one or more of the following:
   • A vitamin
   • A mineral
   • An herb or botanical
   • An amino acid
   • A dietary substance intended to increase total dietary intake
   • A concentrate, metabolite, constituent, extract, or combination of the above ingredients
2. The product must be intended for ingestion and cannot be marketed as a conventional food or a sole item within a meal.

The FDA regulates dietary supplements under the Dietary Supplement Health and Education Act (DSHEA) of 1994. DSHEA prohibits the marketing of adulterated or misbranded supplements. Manufacturers are responsible for ensuring compliance with DSHEA and FDA labeling regulations.

Supplement labels cannot claim to diagnose, treat, or cure diseases. Structure-function claims are permitted but must include an FDA disclaimer.

Banned substances and doping regulations

The World Anti-Doping Agency (WADA) oversees international doping regulations and maintains a standardized list of prohibited substances. In the United States, the United States Anti-Doping Agency (USADA) governs doping control for the U.S. Olympic and Paralympic movement. Professional sports leagues may establish their own anti-doping policies, which can differ from WADA and USADA standards.

Other organizations, including Major League Baseball (MLB), the National Collegiate Athletic Association (NCAA), and the National Football League (NFL), maintain separate lists of banned substances and associated penalties. Athletes, coaches, and strength and conditioning professionals need to stay current on the rules that apply to their sport and level of competition.

Commonly prohibited substances in athletic competition

The following categories of substances are subject to anti-doping regulations. Exact rules may vary depending on the governing body (e.g., WADA, NCAA, or professional leagues).

• Stimulants: Amphetamine, ephedrine, and methamphetamine are banned. Caffeine is not prohibited by WADA but is monitored, while the NCAA bans caffeine at high urine concentrations (≥15 µg/mL).
• Anabolic agents: Testosterone, nandrolone, stanozolol, and other anabolic steroids.
• Alcohol and beta-blockers: Prohibited in sports requiring fine motor control, such as archery and shooting, typically during in-competition testing only.
• Diuretics and masking agents: Substances that can alter drug test results or manipulate body weight.
• Substances of abuse and cannabinoids: Includes heroin, cocaine, and synthetic cannabinoids. Cannabis (THC) is prohibited in-competition.
• Peptide hormones and analogs: Growth hormone (hGH), erythropoietin (EPO), and related compounds.
• Anti-estrogens: Tamoxifen, formestane, and other agents used to counteract estrogenic effects.
• Beta-2 agonists: Medications such as salbutamol and formoterol. Some inhaled forms are permitted at defined therapeutic doses or with a therapeutic use exemption (TUE).