Ligandrol (LGD-4033)

What it is

Ligandrol is a small, non-steroidal molecule with the development code LGD-4033. Under the name VK5211, the company Viking Therapeutics tested the same agent in older people after a hip fracture, a situation in which rapid muscle loss decides on independence.

In the scene, Ligandrol has a different reputation: stronger than ostarine, intended for building rather than maintaining. There is no head-to-head comparison in humans for this classification; it is based on user reports.

How it is supposed to work

SARM stands for selective androgen receptor modulator. The concept dates from 1999 and is modeled on the selective estrogen receptor modulators: an agent is meant to switch on the same receptor in one tissue and hardly at all in another. For the androgen receptor, that means: muscle and bone yes, prostate and skin as little as possible.

Ligandrol binds the androgen receptor with high affinity and is orally active. Because it is not a steroid, it is not converted to DHT or estrogen. A critical review from 2025 points out that part of the apparent selectivity stems precisely from this and that no head-to-head comparison with classic androgens exists.

The study in young men

The most important peer-reviewed paper appeared in 2013. 76 healthy men aged 21 to 50 took Ligandrol at three dose levels or placebo for 21 days and were then followed for another 5 weeks. Lean mass rose dose-dependently, at the highest level by about 1.2 kg more than under placebo. Fat mass did not change.

For three weeks without prescribed training, that is a clear signal, and it shows that the agent does in humans what it was built for. Leg strength, however, remained unchanged. The authors themselves write that longer studies must clarify whether function and health benefit.

After hip fracture

In Viking’s phase 2 study, 108 people aged 65 and over received VK5211 or placebo for 12 weeks after hip fracture surgery. Lean mass rose placebo-adjusted by 4.8, 7.2 and 9.1 percent, depending on the dose level, that is, by up to 3.1 kg. The primary endpoint was reached.

For walking distance and daily functioning there were only numerical improvements, which the study was not designed to detect. According to the registry, 79 of the 108 participants were analyzed. A peer-reviewed full publication could not be found as of September 2026, and Viking has not announced a phase 3 study.

What users report

Users describe a rapid increase in weight and strength within a few weeks, often with some water retention, and use Ligandrol mainly in building phases. Blood tests showing lowered testosterone and HDL are shared just as often. A published single case from 2022 measured this precisely: a 25-year-old took Ligandrol together with MK-677 for 5 weeks. Lean mass rose by 3.1 percent, but fat mass by 15.4 percent; HDL fell by 36.4 percent, the liver value ALT rose by 205.0 percent and total testosterone fell by 62.3 percent. Most values normalized after stopping, fat mass and LDL did not.

What the studies show

Basaria et al., Journals of Gerontology 2013

Randomized, placebo-controlled study with 76 healthy men aged 21 to 50, 21 days, three dose levels. Lean mass rose dose-dependently, at the highest level about 1.2 kg above placebo; fat mass and leg strength unchanged. Total testosterone, SHBG, HDL and triglycerides fell dose-dependently and returned after stopping. Liver values, PSA and blood count remained unchanged.

VK5211 after hip fracture, registry results 2017

Randomized phase 2 with 108 patients aged 65 and over, 12 weeks, three dose levels against placebo. Lean mass placebo-adjusted plus 4.8, 7.2 and 9.1 percent, primary endpoint reached. Function only exploratory and without significant difference. So far published only in the trial registry and as a company announcement.

Cardaci et al., Experimental Physiology 2022

Case report of a 25-year-old user who combined Ligandrol with MK-677 for 5 weeks. Lean mass plus 3.1 percent, fat mass plus 15.4 percent, HDL minus 36.4 percent, ALT plus 205.0 percent, total testosterone minus 62.3 percent, bone density minus 2.1 percent. A single person, two agents, but precisely measured.

Where the data stop

More mass does not yet mean more strength here. In the study in young men, leg strength stayed the same; after hip fracture, the function data were exploratory and not significant. Overall there are only two controlled studies, both short, 21 days and 12 weeks, and the longer one has not been published in peer-reviewed form. The usage patterns of the scene, over weeks and often combined with other agents, have not been tested by anyone under controlled conditions. Measurements were taken by DXA, which counts water as well, and for an agent that users say causes water retention, that is no minor matter. There are no controlled data on safety beyond 12 weeks.

Status, approval and legal

Ligandrol is not approved as a medicine anywhere in the world; after phase 2, Viking has not announced any further study for VK5211. The US Food and Drug Administration (FDA) makes clear that SARMs are not dietary supplements but unapproved drugs. In Germany, Ligandrol is listed by name in the annex to the Anti-Doping Act; manufacture and trade for the purpose of doping in sport are prohibited, as are acquisition and possession of a not insignificant quantity for this purpose. The World Anti-Doping Agency lists LGD-4033 in the 2026 list under S1.2 and prohibits it at all times. Doping analysis detects long-lived metabolites, and a positive test after transmission through intimate contact has even been described.

Safety

Within just 21 days, total testosterone, SHBG and HDL fell dose-dependently in the controlled study, and at the highest level FSH and free testosterone as well; the values returned after stopping, and liver values remained unchanged there. Outside of studies, the picture is different: several peer-reviewed case reports describe severe cholestatic liver damage in users, including a 37-year-old with a bilirubin 30 times above normal and bile duct loss on biopsy. According to one review, the typical pattern is a creeping jaundice with a sharp rise in bilirubin and only slightly elevated liver enzymes. A systematic review found ALT increases in a mean of 7.1 percent of SARM-exposed participants in studies. The FDA also names heart attack, stroke, infertility and miscarriage for SARMs. And in a JAMA analysis, only 52 percent of the products sold as SARMs contained a SARM at all. Not for pregnant women, not with liver disease, not for competitive athletes.

Sources

• Basaria et al., Journals of Gerontology A 2013 — LGD-4033 in 76 healthy young men
• ClinicalTrials.gov NCT02578095 — VK5211 after hip fracture, registry results
• Bond et al., Frontiers in Endocrinology 2025 — critical appraisal of SARMs
• Cardaci et al., Experimental Physiology 2022 — case report LGD-4033 and MK-677
• Barbara et al., ACG Case Reports Journal 2020 — liver injury from Ligandrol
• Wallstab et al., Zeitschrift für Gastroenterologie 2023 — Ligandrol-induced liver injury
• Mohideen et al., Journal of Clinical and Translational Hepatology 2023 — SARMs as liver toxins
• Vignali et al., Journal of Xenobiotics 2023 — systematic review of SARM safety
• Van Wagoner et al., JAMA 2017 — contents of SARM products sold online
• FDA 2025 — warning about bodybuilding products containing SARMs