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 |
|---|---|---|---|---|---|
Generic | 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 |
GenericSelected | 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 here..lied during the dispute