At a glance
Effects
- Lean muscle growth: Promotes significant gains in lean muscle mass via AR-mediated protein synthesis and myostatin suppression through follistatin upregulation, as shown in C2C12 myoblast studies [1][2].
- Strength: Greater muscle mass and myogenic factor activation may translate to increased strength and power output; gains reported anecdotally within 10–14 days of use [8].
- Bone support: Cell studies show YK-11 induces osteoblast-specific differentiation markers (osteoprotegerin, osteocalcin), suggesting a potential bone-density benefit — though this has not been confirmed in human trials [7].
- Minimal water retention: Unlike testosterone or many anabolic steroids, YK-11 does not aromatise and is associated with dry, dense muscle gains rather than oedema [8].
Steroidal SARM / Myostatin inhibitor
~12 hours (estimated; no confirmed human PK data) [4]
Oral (research chemical)
Banned by WADA & USADA; not FDA-approved; research chemical only [12][13]
None published — all evidence preclinical [3][4]
About YK-11
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
YK-11 is a synthetic steroidal compound classified as both a selective androgen receptor modulator (SARM) and a myostatin inhibitor, derived from a dihydrotestosterone (DHT) scaffold [1][2]. It is used in the performance and bodybuilding community for its dual anabolic action — promoting lean muscle growth and potentially supporting bone density — though it has never undergone human clinical trials [3][4].
How it works
YK-11 acts as a gene-selective partial agonist of the androgen receptor (AR), triggering anabolic signalling in muscle cells without fully activating the receptor the way testosterone does [1][2]. Its defining feature is the simultaneous upregulation of follistatin (FST) — a glycoprotein that binds directly to myostatin and prevents it from signalling through activin receptors on muscle cells [2][5]. Myostatin is a natural brake on muscle growth; by raising follistatin, YK-11 suppresses this brake and allows muscle protein synthesis to proceed beyond typical physiological limits [5]. In cell studies (C2C12 myoblasts), YK-11 also induced key myogenic regulatory factors — MyoD and Myf5 — and stimulated osteoblast markers such as osteoprotegerin and osteocalcin, suggesting a bone-supporting action [6][7]. All mechanistic evidence to date is from in-vitro and preclinical animal models; no human pharmacokinetic or pharmacodynamic data have been published [3][4].
Risks & side effects
Most important: YK-11 has zero published human safety or clinical trials, making its true toxicity profile unknown [3][4]. Its steroidal backbone raises concern for dose-dependent testosterone suppression and potential liver enzyme elevation — both of which may be serious but currently lack controlled human evidence [9][10].
Common
- Testosterone suppression — dose-dependent reduction in endogenous testosterone production commonly reported; may cause low libido and fatigue post-cycle [9][10].
- Joint discomfort — associated with myostatin inhibition and rapid muscle mass changes, can cause inflammation and joint pain [3].
- Mood changes / irritability — linked to hormonal fluctuations from androgen receptor stimulation and testosterone suppression [3][4].
- Mild androgenic effects — acne and hair thinning reported, especially in those genetically predisposed [4][10].
Serious
- Liver strain / hepatotoxicity — due to its partially steroidal, orally active structure, YK-11 may elevate liver enzymes, particularly at higher doses or on longer cycles; no confirmed threshold exists [9][10].
- Cardiovascular impact — YK-11 has been associated with increased cardiac stress markers in animal studies and may adversely affect lipid balance [9][10].
- Hormonal shutdown — high doses (15–20 mg/day) reported by users to cause near-complete suppression of endogenous testosterone, potentially requiring extended post-cycle therapy [10].
- Unknown long-term systemic effects — no human trials; long-term impact on liver, kidneys, cardiovascular, endocrine, and reproductive systems is entirely uncharacterised [3][4].
Rare
- Potential neurological / hippocampal effects — a 2024 PubMed study found YK-11 induced oxidative stress and mitochondrial dysfunction in rat hippocampus; human relevance is unknown [11].
- Soft-tissue injury risk — reduced myostatin may impair tendon and collagen repair alongside rapid muscle growth, potentially increasing soft-tissue injury risk [9].
- Possible DNA toxicity — some animal data suggests genotoxic potential; human evidence is absent [3].
Safety & harm reduction
- Individuals under 21 or still undergoing puberty — risk of permanent endocrine disruption [13].
- Women who are pregnant, breastfeeding, or planning pregnancy — androgenic effects and unknown foetal risk.
- Anyone with pre-existing liver disease, elevated liver enzymes, or hepatic impairment — steroidal structure increases hepatotoxicity risk [9][10].
- Anyone with diagnosed or suspected cardiovascular disease, or a history of heart attack — potential cardiac stress marker elevation [9].
- Competitive athletes subject to WADA, USADA, or NCAA testing — YK-11 is a banned substance and detectable in doping control samples [12][13].
- Beginners or first-time SARM users — potency and side-effect profile not appropriate for inexperienced users [13].
- Liver function tests (AST, ALT, ALP, bilirubin) — baseline before cycle, mid-cycle, and 4 weeks post-cycle [10].
- Full blood count and lipid panel (LDL, HDL, triglycerides) — baseline and post-cycle [9][10].
- Total and free testosterone, LH, FSH — to assess degree of suppression before and after cycle [9].
- Blood pressure — monitor throughout cycle given cardiovascular stress signals [10].
- Other SARMs or anabolic steroids — stacking significantly increases testosterone suppression and hepatotoxicity risk [10].
- Hepatotoxic medications (e.g. acetaminophen at high doses, statins, antifungals) — additive liver stress [10].
- Anticoagulants / blood thinners — androgenic compounds can affect clotting factors; monitor INR if relevant.
- CYP450-metabolised drugs — YK-11 is metabolised via cytochrome P450 enzymes, creating potential for drug-drug interactions [11].
- Cycle length — keep cycles to 6 weeks or fewer to limit cumulative liver and hormonal strain [10].
- Liver support — consider N-acetyl cysteine (NAC) or TUDCA during cycle, especially at doses above 5 mg/day [10].
- Post-cycle therapy (PCT) — due to testosterone suppression, a SERM-based PCT (e.g. Nolvadex/Clomid) is strongly recommended immediately after cycle completion [9][13].
- Allow full recovery — minimum 8–12 weeks off between cycles; confirm testosterone recovery via bloodwork before starting again [13].
- Dose conservatively — start no higher than 5 mg/day and do not exceed 10 mg/day given lack of human safety data [10].
Dosage context
No clinically validated dosing exists for YK-11 — zero human trials have been published [3][4]. Community-reported ranges (not a prescription or endorsement) typically cite 5–10 mg/day for lower-risk use, with some experienced users going up to 15 mg/day split into two doses to maintain plasma levels; cycles are generally capped at 6 weeks [10]. Sources consistently note that risk of testosterone suppression and liver toxicity rises steeply above 10 mg/day [10]. These figures are derived from anecdotal and vendor reports only — use extreme caution and seek medical guidance.
Sources
- 1.Swolverine — YK-11 as Myostatin Inhibitor
- 2.Substack / TypeIIX — YK-11 SARM Exception
- 3.Swolverine — YK-11 Side Effects
- 4.Behemoth Labz — YK-11 Side Effects Explained
- 5.MedKoo — YK-11 Pharmacology Profile
- 6.PubMed — YK-11 Hippocampal Effects (2024)
- 7.Sports Technology Labs — YK-11 Research Chemical
- 8.FitScience — YK-11 Complete Guide
- 9.Swiss Pharmaceuticals — YK-11 Side Effects
- 10.Swolverine — YK-11 Dosage Guide
- 11.ScienceDirect — YK-11 Oxidative Stress & Hippocampus (2023)
- 12.DadBod2.fit — YK-11 Myostine Guide 2025 (link unavailable)
- 13.Muscle and Brawn — YK-11 Complete Review
- 14.ScienceDirect — YK-11 as Preventative Supplement for Sepsis (2021)
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.
Other options for YK-11· 3 offers
Same compound from different labs/brands and pack sizes. Tap a row to switch brand — the price and buy button update instantly.
This compound comes in different forms (e.g. injectable vs oral vs topical). Cost per mg is only comparable within the same form.
| Brand | Form | Strength | Pack | Price | Per mg |
|---|---|---|---|---|---|
GenericSelected | oral-liquid | 20 mg/ml | 50 ml | 129,99 € | €0.130/mg |
Intex Pharma | blister-pack | 10 mg/tab | 60 tab | 134,99 € | €0.225/mg |
Generic | oral-liquid | 20 mg/ml | 100 ml | 219,99 € | ★€0.110/mg |
Substance reviews(1)
Independent reviews of this compound from the wider market — about the substance, not our delivery.
- ★★★★★2 months ago
everything leaked ,do not order of this person,he drops ships from differnt countrys and doesnt even know what hes sending ,spoke to me like shit and just waited the dipute out,pos