Performance-enhancing drugs (PEDs) are substances or methods used to improve athletic ability beyond what training alone can achieve. They range from synthetic hormones that build muscle to compounds that boost oxygen delivery, sharpen focus, or steady a shaking hand. The World Anti-Doping Agency maintains a prohibited list that spans more than a dozen categories of substances and methods, covering everything from anabolic steroids to gene doping.
The Major Categories of PEDs
PEDs aren’t a single type of drug. They fall into broad groups based on what they do in the body. The most commonly discussed categories include anabolic agents (steroids and related compounds), peptide hormones and growth factors (like EPO and human growth hormone), stimulants, beta-blockers, diuretics and masking agents, and several prohibited methods such as blood transfusions and gene doping.
Some substances are banned at all times, both in and out of competition. Others, like stimulants and narcotics, are only prohibited during competition. A few, like beta-blockers, are banned only in specific sports where they offer a clear advantage. Cannabinoids are prohibited in competition, though CBD is specifically excluded from the ban.
Anabolic Steroids and Muscle Growth
Anabolic steroids are synthetic versions of testosterone. They work by activating the same receptors that natural testosterone uses, increasing the number of those receptors in skeletal muscle and ramping up protein synthesis. The result is faster muscle growth, greater strength, and quicker recovery between workouts. Athletes can train harder and more frequently than their bodies would otherwise allow.
This category also includes newer compounds like selective androgen receptor modulators (SARMs), which attempt to target muscle tissue more precisely. Despite marketing claims, SARMs carry many of the same risks and are banned under the same rules as traditional steroids.
EPO and Blood Doping
Erythropoietin, widely known as EPO, is a hormone that tells the body to produce more red blood cells. More red blood cells means more oxygen delivered to working muscles, which directly improves endurance. In clinical studies, a 30% increase in hemoglobin concentration has been associated with roughly a 15% improvement in aerobic capacity. For an elite endurance athlete, that margin is enormous.
Blood doping achieves a similar effect through different means. Athletes either transfuse stored blood back into their bodies before competition or use synthetic oxygen carriers. Both approaches are banned as prohibited methods. The goal is always the same: get more oxygen to the muscles for longer.
Human Growth Hormone
Human growth hormone (HGH) occupies a complicated space in the PED world. Athletes use it primarily for recovery and injury repair rather than raw strength. Research on ACL reconstruction patients found that those receiving HGH injections had 29% greater knee extension strength compared to a placebo group. The treatment also appeared to protect cartilage, with a 36% lower level of an enzyme associated with cartilage breakdown.
HGH plays a larger role in connective tissue repair and collagen synthesis than in building muscle mass directly. This makes it particularly attractive to athletes recovering from injury or looking to maintain joint health under heavy training loads.
Stimulants and Cognitive Enhancers
Stimulants work by increasing levels of dopamine and norepinephrine in the brain, which improves focus, alertness, and reaction time. In an athletic context, they also reduce how hard exercise feels. Athletes on stimulants still experience fatigue, but they perceive it as less intense, allowing them to push further before their body signals them to stop.
This carries a serious safety trade-off. Stimulants raise core body temperature and mask the warning signs of exhaustion, increasing the risk of heat injury and overexertion. The body’s natural alarm system is effectively muted.
Caffeine sits at the milder end of this spectrum. It blocks adenosine receptors (the chemical signal that makes you feel sleepy), improves short-term memory, and sharpens concentration. It’s widely used and currently not prohibited by anti-doping authorities, though it was banned in the past. Stronger compounds like amphetamines and modafinil increase wakefulness and attention through more potent effects on dopamine, and both remain prohibited in competition.
Beta-Blockers in Precision Sports
Beta-blockers slow heart rate and reduce tremor, which is why they’re banned in sports like archery, shooting, darts, and golf. Competition stress causes elevated heart rate and fine muscle tremors that can throw off aim. Beta-blockers dampen the body’s stress response, keeping hands steadier and heartbeats more predictable. Interestingly, at least one study commissioned by WADA found that despite lowering heart rate, beta-blockers didn’t measurably improve archery performance scores in a controlled setting. The ban remains in place based on their known physiological effects.
Diuretics and Masking Agents
Diuretics don’t enhance performance directly. They force the kidneys to expel water, which serves two purposes: rapid weight loss to meet a lower weight class, and diluting urine to make other banned substances harder to detect. This is why they’re classified alongside masking agents. Any substance that interferes with the detection of another prohibited drug is itself prohibited.
How PED Use Is Detected
Traditional drug testing works by identifying banned substances or their breakdown products in urine or blood samples. But athletes have become sophisticated at timing their use to avoid detection windows, which led to the development of the Athlete Biological Passport (ABP).
The ABP doesn’t look for drugs directly. Instead, it tracks an athlete’s biological markers over time, building an individual profile of blood values and steroid levels. The blood module, introduced first, monitors red blood cell variables to catch blood doping. A steroid module added in 2014 tracks the natural ratios of hormones in urine. When values swing outside an athlete’s established baseline, it raises a flag, even if no specific substance is identified in that sample.
Cardiovascular and Long-Term Health Risks
The health consequences of PED use, particularly anabolic steroids, extend well beyond suspension from sport. A large study published in Circulation found that steroid users had a ninefold increased incidence of cardiomyopathy, a disease of the heart muscle, compared to non-users. Among those cases, over half involved the heart muscle thickening abnormally without any blockage in the arteries.
Steroid use is also linked to unfavorable cholesterol ratios, high blood pressure, blood clotting abnormalities, and accelerated coronary artery disease. Imaging studies of both active and former users have shown increased heart mass, reduced pumping efficiency, and impaired relaxation of the heart between beats. Notably, some of these changes persisted even in people who had stopped using steroids, suggesting the damage is not fully reversible.
EPO carries its own risks. Thickening the blood with excess red blood cells raises the likelihood of clots, stroke, and heart attack, particularly during sleep or periods of dehydration when blood flow slows. Stimulant abuse can trigger cardiac arrhythmias, dangerously high body temperature, and in rare cases, sudden death during exertion.
Gene Doping: The Newest Frontier
Gene doping involves altering an athlete’s DNA or gene expression to enhance performance. This could mean inserting genes that boost EPO production, increase muscle fiber growth, or improve oxygen utilization at the cellular level. No confirmed cases of gene doping have been publicly identified in professional sport, but the method is explicitly banned. It represents a category that anti-doping authorities are preparing for rather than reacting to, using advances in genetic sequencing to develop detection methods before widespread adoption occurs.