LGD-4033, also known as Ligandrol, is a selective androgen receptor modulator (SARM), a class of experimental drugs designed to stimulate muscle and bone growth without the broader hormonal effects of anabolic steroids. It was originally developed for medical conditions involving muscle wasting, such as muscular dystrophy, osteoporosis, and cancer-related muscle loss. Despite circulating widely in fitness and bodybuilding communities, LGD-4033 is not approved by the FDA for any use and cannot be legally sold as a dietary supplement or medication in the United States.
How LGD-4033 Works
LGD-4033 binds to androgen receptors, the same cellular targets that testosterone activates. What makes it a “selective” modulator is that it preferentially targets androgen receptors in muscle and bone tissue rather than in organs like the prostate, skin, or liver. In animal studies, it increased muscle mass and strengthened bone while showing minimal activity in the prostate, which is one of the main sources of side effects with traditional anabolic steroids.
The compound binds to androgen receptors with high affinity, at a concentration of roughly 1 nanomolar. That’s comparable to testosterone itself, which helps explain why even small amounts can produce noticeable effects on muscle tissue. It’s taken orally, unlike many anabolic steroids that require injection, which is part of its appeal in recreational settings.
What the Clinical Data Shows
LGD-4033 has been studied in at least one Phase I clinical trial in healthy young men, published in The Journals of Gerontology. The trial confirmed the compound’s anabolic activity in muscle tissue and anti-resorptive effects in bone, meaning it both builds new bone and slows the breakdown of existing bone. These findings matched what had already been observed in animal models.
The compound was initially explored as a potential treatment for people losing muscle due to serious illness. Conditions like muscular dystrophy, osteoporosis, and the muscle wasting that accompanies cancer treatment were all targets. However, LGD-4033 has never advanced far enough through human trials to receive regulatory approval for any of these uses.
Hormone Suppression
One of the most important things to understand about LGD-4033 is that it suppresses your body’s natural hormone production. Because it activates the same receptors as testosterone, your brain registers higher-than-normal androgenic signaling and dials back its own production in response. This means total testosterone, sex hormone-binding globulin, and follicle-stimulating hormone levels all drop during use.
This suppression is dose-dependent: higher amounts cause a larger drop. After stopping, hormone levels typically recover over several weeks, but the timeline varies. During that recovery window, users commonly report fatigue, low mood, and reduced sex drive, which is why post-cycle recovery protocols are a constant topic of discussion in bodybuilding forums. The FDA lists both sexual dysfunction and infertility as risks associated with SARMs as a class.
Liver Safety Concerns
SARMs as a group carry a real risk of liver damage. A systematic review published in the Journal of Xenobiotics found that elevated liver enzymes, specifically a marker called ALT, appeared in an average of 7.1% of clinical trial participants taking various SARMs. Most of those elevations were mild and resolved within about 28 days, even while the person continued taking the drug. But that wasn’t always the case. Several subjects across multiple trials experienced ALT spikes greater than four times the upper limit of normal, with the highest recorded value reaching 343 IU/L.
Beyond clinical trials, 15 case reports of drug-induced liver injury tied to SARMs were identified in the same review. Every one of those patients was male, with an average age of about 34. The review’s authors concluded that clinical trials “clearly demonstrated a signal” for liver injury potential, even though the exact mechanism isn’t fully understood. One study found an association between SARM use and a biomarker linked to hepatocellular (liver cell) damage.
This risk is amplified in recreational settings, where products are unregulated. Independent lab testing has repeatedly shown that SARM products sold online often contain incorrect doses, different compounds than listed on the label, or additional unlisted ingredients.
Other Known Side Effects
The FDA’s safety warning on SARMs lists a range of potential health consequences beyond liver injury. These include increased risk of heart attack or stroke, psychosis or hallucinations, sleep disturbances, sexual dysfunction, testicular shrinkage, infertility, and pregnancy miscarriage. Not all of these have been observed specifically with LGD-4033 in controlled settings, but the FDA applies them to the SARM category broadly based on available evidence and adverse event reports.
Cholesterol changes are another concern. Androgens in general tend to lower HDL (“good”) cholesterol, and SARMs appear to follow the same pattern. A drop in HDL shifts your cardiovascular risk profile in the wrong direction, particularly if use extends over weeks or months.
Legal and Regulatory Status
LGD-4033 occupies a gray zone that confuses a lot of people. It is not a controlled substance in the same legal category as anabolic steroids in most countries. However, the FDA has made its position clear: SARMs are unapproved drugs. They cannot be legally marketed as dietary supplements, and the “sold for research purposes only” label that many vendors use does not change that classification. The FDA has issued warning letters to companies selling SARMs and has pursued criminal actions against some distributors.
For athletes, the situation is more straightforward. The World Anti-Doping Agency (WADA) lists LGD-4033 by name under category S1.2, “Other Anabolic Agents,” on its Prohibited List. It is banned both in and out of competition. Multiple athletes across various sports have received sanctions after testing positive for Ligandrol, including cases where athletes claimed contaminated supplements were the source. WADA testing can detect LGD-4033 metabolites for weeks after a single dose.
Why People Use It Despite the Risks
The appeal of LGD-4033 comes down to a simple pitch: muscle growth with fewer side effects than steroids. Because it’s taken as a pill rather than injected, and because animal data shows it spares the prostate and other organs that steroids hit hard, it gets marketed in fitness circles as a “safer” alternative. The oral convenience, the selectivity story, and easy online availability all contribute to its popularity.
But “safer than steroids” is not the same as “safe.” The compound has never completed the full clinical trial process that would establish a proper safety profile in humans. The longest controlled study lasted only 21 days. Everything beyond that, including the 8- to 12-week cycles commonly discussed online, is uncharted territory from a medical standpoint. Users are essentially running their own uncontrolled experiments with a drug whose long-term effects on the heart, liver, hormones, and fertility remain unknown.