Anabolic steroids are synthetic versions of testosterone prescribed for a handful of medical conditions, most commonly low testosterone in men. They are also widely used outside of medicine to build muscle and enhance athletic performance, which accounts for the majority of their use worldwide. In the U.S., anabolic steroids are classified as Schedule III controlled substances, meaning they require a prescription and carry legal penalties for unauthorized possession.
Prescribed Medical Uses
The most common medical reason for prescribing anabolic steroids is male hypogonadism, a condition where the body doesn’t produce enough testosterone on its own. Symptomatic testosterone deficiency affects up to 2% of the general male population and is defined by blood levels below roughly 300 ng/dL combined with symptoms like fatigue, low sex drive, and loss of muscle mass. Treatment guidelines recommend maintaining testosterone within a mid-normal range of 450 to 600 ng/dL, with regular monitoring of blood counts and prostate health.
Beyond low testosterone, doctors prescribe anabolic steroids to counteract severe muscle wasting. Patients with HIV/AIDS, chronic obstructive pulmonary disease, and certain cancers can lose dangerous amounts of lean body mass, a condition called cachexia. Clinical trials have shown that testosterone and related compounds improve body weight, lean mass, and muscle strength in these patients with an acceptable safety profile. One compound in particular, oxandrolone, has been approved for decades as an oral option for both men and women experiencing weight loss from surgery, infection, or other critical illness. It carries less risk of liver problems and masculinizing side effects than other steroids, making it better tolerated in women.
Severe burn patients represent another important use case. In critically burned children, oxandrolone improved muscle protein balance by boosting the efficiency of protein synthesis, essentially redirecting more of the body’s available amino acids toward rebuilding muscle rather than breaking it down. Studies have also documented shortened wound healing times in severely burned adults treated with the drug during hospitalization.
In adolescent boys with delayed puberty, low doses of testosterone (roughly one-third to one-fifth of the adult replacement dose) are given as monthly injections for about six months to jumpstart development. Certain types of breast cancer in women have also been treated with anabolic steroids, though this is less common today.
How They Work in the Body
Anabolic steroids work by binding to androgen receptors found throughout the body, particularly in muscle tissue. Once attached, they switch on genes that control muscle growth, triggering two key processes: increased protein synthesis and the proliferation of muscle satellite cells, which are the stem cells responsible for repairing and building new muscle fibers. Steroids also increase the number of androgen receptors themselves, creating a feedback loop where muscles become increasingly responsive to the hormones.
At higher doses, steroids activate additional signaling pathways along muscle cell membranes that further amplify protein production. The net effect is that muscle tissue accumulates protein faster than it breaks it down, leading to growth in both size and strength.
Non-Medical Use for Performance
The performance-enhancing effects of anabolic steroids are well documented and substantial. In a landmark controlled study, men who received weekly testosterone injections for 10 weeks gained significant muscle size and strength even without exercising. Those who combined the injections with resistance training saw dramatically larger gains than either exercise or testosterone alone. A more recent meta-analysis found that steroid use alongside exercise improved strength by an average of 52% compared to non-users, along with measurable improvements in body composition.
There is a clear dose-response relationship: higher weekly doses produce greater changes in muscle mass and performance, which is why non-medical users typically take doses far beyond what a doctor would prescribe. Supraphysiological doses in the range of 200 to 600 mg per week have been shown to significantly boost both body composition and exercise performance in controlled trials. This is what drives use among bodybuilders, powerlifters, and athletes in strength-dependent sports, despite the health risks and the fact that most sporting organizations ban these substances.
Risks to the Heart and Liver
The cardiovascular effects of anabolic steroids are among the most serious concerns. Steroid use disrupts cholesterol balance by lowering HDL (protective cholesterol) and raising LDL (harmful cholesterol), which increases the risk of coronary artery disease and stroke. Imaging studies comparing steroid users to non-users have revealed pathological thickening of the heart muscle, a condition called left ventricular hypertrophy. In some cases, this has progressed to myocardial scarring even in users with otherwise normal coronary arteries. Steroids appear to drive this by activating androgen receptors directly in heart muscle cells, stimulating excessive protein synthesis and growth.
Liver toxicity is primarily a concern with oral steroids that have been chemically modified (a change called 17-alpha alkylation) to survive digestion. This modification forces the liver to process the compound in ways that can cause cholestatic jaundice, where bile flow is blocked, leading to yellowing of the skin and eyes. Rarer but more serious liver complications include peliosis hepatis (blood-filled cysts in the liver) and liver tumors. Injectable steroids that bypass the digestive system generally carry less liver risk.
Shutdown of Natural Hormone Production
When you introduce large amounts of synthetic testosterone, the brain detects the surplus and dials down its own signals to produce more. Specifically, the hypothalamus reduces its release of the hormones that tell the pituitary gland to stimulate the testes. This suppression is dose-dependent: higher doses and longer use cause deeper shutdown. The result, once steroids are stopped, is a state called anabolic steroid-induced hypogonadism, where natural testosterone production is severely depressed.
Recovery follows a fairly predictable timeline for most users. Gonadotropins, the pituitary hormones that drive testosterone production, typically return to normal within three to six months after stopping. Testosterone itself shows near-complete recovery over a similar period, though full restoration to pre-use levels is not guaranteed in every case. During this recovery window, users commonly experience fatigue, depression, loss of libido, and rapid loss of the muscle they gained, which is one reason many users struggle to stop or cycle back on repeatedly.
Legal Status in the United States
Anabolic steroids were added to the Controlled Substances Act as Schedule III drugs, placing them in the same regulatory category as certain barbiturates and other substances with recognized medical use but potential for abuse. This means possessing anabolic steroids without a valid prescription is a federal offense. Manufacturing or distributing them carries stiffer penalties. Despite this, anabolic steroids remain widely available through underground labs and international sources, and non-medical use continues to be common in gym and athletic communities.