hormoneNot FDA-approvedResearch chemicalNo published human trials; sold only as an unregulated research chemical
YK-11Benefits, Dosage & Interactions
Also known as: Myostatin SARM
YK-11, also known by its aliases Myostatin SARM or Myostatin-inhibiting SARM, is a synthetic investigative compound classified as a selective androgen receptor modulator (SARM). Research on YK-11 focuses on muscle and strength and testosterone support. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Preclinical — Animal and in-vitro studies only, no published human RCTs.
Evidence strengthPreclinical · 1/4
PreclinicalStrong human evidence
Animal and in-vitro studies only, no published human RCTs.
Plasma half-life
Not established
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
Reported for YK-11 in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the YK-11 entry is written from. Each number matches an inline marker above.
- [1]Detection of selective androgen receptor modulator YK-11 in a doping control sampleSobolevsky T, Kucherova Y, Ahrens B · Drug Testing and Analysis · 2024 · Peer-reviewed · PMID 37946705
- [2]Equine metabolism of the selective androgen receptor modulator YK-11 in urine and plasma following oral administrationHarding C, Viljanto M, Habershon-Butcher J, Taylor P, Scarth J · Drug Testing and Analysis · 2023 · Peer-reviewed · PMID 36519889
- [3]Detection of nonsteroidal and steroidal selective androgen receptor modulators in equine hair after oral administrationsSo YM, Kong FK, Kwok WH, Kwok KY, Wan TSM, Ho EN · Drug Testing and Analysis · 2025 · Peer-reviewed · PMID 39001560
How to track YK-11 doses
YK-11 is tracked as a protocol rather than a single reminder: a vial with a concentration, a schedule that may be titrated or cycled, and a rotation of injection sites. Here is the record that keeps all three consistent.
- 1
Record the vial and concentration
Log the vial strength and the volume of bacteriostatic water you added so YK-11 is stored as a concentration rather than a guess. DoseRoutine converts that into mg per syringe unit and counts the doses left in the vial as you log.
- 2
Set the schedule, not just a reminder
Enter the dose in mg and the frequency. Cycled protocols get a start and end date so the history stays accurate when YK-11 comes out of the routine.
- 3
Rotate and log the injection site
Pick the site at the moment you log the dose. The site map shows what you used last and how recently, which is the part that drifts fastest when two compounds run on different frequencies.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
Review YK-11 alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.
What to log each time
- Dose in mg and the syringe units it worked out to
- Vial: reconstitution date, concentration, doses remaining
- Injection site and time
- Any side effects in the 24 h after the dose
References & Evidence
Sources on this page that document YK-11 dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is YK-11 studied for?
What is YK-11?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
YK-11, also known by its aliases Myostatin SARM or Myostatin-inhibiting SARM, is a synthetic investigative compound classified as a selective androgen receptor modulator (SARM). Despite sharing some structural similarities with steroids due to its steroidal backbone, YK-11 is typically categorized within the SARM class due to its proposed mechanism of action involving selective androgen receptor (AR) agonism. However, its unique characteristic lies in its additional proposed role as a myostatin inhibitor, which differentiates it from many other SARMs that primarily focus on AR modulation. Myostatin is a protein that naturally limits muscle growth; by potentially inhibiting this protein, YK-11 is hypothesized to allow for increased muscle development beyond natural genetic limits.
Research on YK-11 has primarily been conducted in cellular and animal models, with human data remaining very limited. Most current understanding is derived from in vitro studies, which have shown YK-11's ability to act as a partial agonist of the androgen receptor and its potential to increase follistatin expression, a protein that directly inhibits myostatin. The compound is not approved for human use by regulatory bodies like the FDA and is considered a research chemical. Due to the lack of comprehensive clinical trials, its full efficacy, safety profile, and long-term effects in humans are not well established. Individuals interested in this compound should be aware of its unapproved status and the significant gaps in scientific knowledge regarding its use.
What does the research say about YK-11?
Tap a section to expand.
YK-11's proposed mechanism of action involves two primary pathways: partial androgen receptor (AR) agonism and potential myostatin inhibition. As a partial AR agonist, YK-11 is thought to bind to androgen receptors in certain tissues, particularly muscle and bone, modulating gene expression associated with anabolic processes. This selective activation is intended to promote anabolism with fewer androgenic side effects compared to traditional anabolic steroids, which typically activate ARs more broadly across various tissues.
The more distinctive aspect of YK-11's mechanism is its potential to inhibit myostatin, a protein that negatively regulates muscle growth. In vitro studies (cellular research) have indicated that YK-11 may increase the expression of follistatin. Follistatin is a naturally occurring glycoprotein that binds to and inactivates myostatin, thereby preventing myostatin from limiting muscle development. By enhancing follistatin levels, YK-11 is hypothesized to reduce the inhibitory effects of myostatin, creating an environment more conducive to muscle hypertrophy and proliferation. This dual mechanism—selective AR agonism coupled with myostatin inhibition—suggests a potentially unique pathway for promoting muscle growth, although further in vivo and human studies are essential to fully elucidate and confirm these effects. (Source: PubChem, research papers on YK-11 in cellular models)
Source for this section: Sources for How does YK-11 work?: Jumps to this entry in the sources and references list at the end of the page.
The purported benefits of YK-11 primarily revolve around its potential to enhance muscle growth and strength, stemming from its dual proposed mechanisms of action. Based on preliminary in vitro (cell culture) research and anecdotal reports (which are not scientific evidence), the main areas of interest include:
* **Increased Muscle Mass:** The primary proposed benefit is a significant increase in lean muscle mass. This is theorized to occur due to YK-11's potential to act as a partial androgen receptor agonist, promoting anabolic processes, and more notably, through its hypothesized inhibition of myostatin via increased follistatin expression. Myostatin's role is to limit muscle growth, and by reducing its activity, YK-11 is speculated to allow muscles to grow beyond their natural genetic potential.
* **Enhanced Strength:** Concurrent with increased muscle mass, users often report improvements in muscular strength. This link is common in compounds that promote muscle hypertrophy, as larger muscle fibers generally correlate with increased force production capabilities.
* **Bone Health:** Like other SARMs, YK-11, through its partial androgen receptor agonism, may exert anabolic effects on bone tissue. Androgen receptors play a role in bone mineral density maintenance, and selective modulation could theoretically contribute to improved bone strength, though this is less emphasized than its muscle-building effects and remains speculative without dedicated research.
It is crucial to reiterate that these benefits are largely theoretical, derived from preliminary cell-level studies and anecdotal accounts. There is a significant lack of robust clinical evidence (human trials) to substantiate these claims. The safety and long-term efficacy of YK-11 in humans are not established. (Source: Preliminary in vitro studies, review of SARMs literature)
Evidence for YK-11's effects predominantly comes from in vitro (cell culture) studies and animal models, with a notable absence of published human clinical trials. A key study, often cited, demonstrated in C2C12 myoblasts (a type of muscle cell line) that YK-11 significantly increased follistatin expression and promoted muscle cell differentiation and growth. This cellular research provided the initial basis for the hypothesis that YK-11 could act as a myostatin inhibitor by upregulating follistatin.
Further in vitro work has explored YK-11's interaction with the androgen receptor (AR). These studies suggest YK-11 acts as a partial agonist of the AR, indicating it binds to the receptor but may elicit a less pronounced or tissue-selective response compared to full agonists like testosterone. This partial agonism is theorized to contribute to its anabolic effects while potentially mitigating some androgenic side effects. However, the exact selectivity and efficacy of this AR agonism in vivo are still not fully characterized.
Animal studies involving YK-11 are limited but have contributed to some understanding of its pharmacokinetics and effects. These studies often observe anabolic effects in terms of muscle mass. However, extrapolating findings from animal models, especially rodents, directly to humans is often not straightforward due to physiological differences.
The absence of human clinical trials means that there is no high-quality evidence regarding its efficacy, optimal dosing, safety profile, or long-term effects in humans. All claims of benefits are currently speculative and based on indirect evidence or unverified anecdotal reports. Regulatory bodies worldwide have not approved YK-11 for any medical use, reflecting the lack of sufficient human safety and efficacy data. (Source: Scientific review articles citing original in vitro research, PubChem)
Given the limited human research on YK-11, a comprehensive understanding of its side effects is lacking. However, based on its proposed mechanism as a selective androgen receptor modulator (SARM) and its steroidal backbone, potential side effects observed with similar compounds or speculated from its activity include:
* **Liver Toxicity:** Although often marketed as 'liver-safe,' some SARMs have raised concerns about potential hepatotoxicity. Due to the lack of human data on YK-11, liver enzyme elevations cannot be ruled out. Regular liver function monitoring would be prudent if this compound were to be used in a research setting.
* **Testosterone Suppression:** As an androgen receptor modulator, YK-11 may lead to suppression of natural endogenous testosterone production, particularly at higher doses or with prolonged use. This suppression can result in symptoms such as fatigue, decreased libido, and mood disturbances. Post-cycle therapy (PCT) is often discussed by users employing such compounds, reflecting concerns over hormonal imbalance.
* **Androgenic Side Effects (Potential):** While SARMs are designed to be tissue-selective to minimize androgenic effects, the steroidal structure and partial AR agonism of YK-11 mean that some androgenic side effects, such as increased hair growth, acne, or male pattern baldness exacerbation, theoretically cannot be entirely excluded, especially in individuals sensitive to androgens.
* **Cardiovascular Strain:** Some SARMs have been linked to adverse changes in lipid profiles (e.g., decreased HDL 'good' cholesterol and increased LDL 'bad' cholesterol), which could potentially increase cardiovascular risk over time. The impact of YK-11 on lipid profiles is not well documented.
* **Hair Loss:** Some anecdotal reports suggest potential hair thinning or acceleration of male pattern baldness, consistent with hormonal alterations.
* **Joint Discomfort:** Some anecdotal reports describe joint dryness or discomfort, possibly related to altered fluid retention or hormonal changes, though this is not scientifically established.
It is critical to emphasize that this list is not exhaustive, and the true incidence and severity of these or other unknown side effects in humans are not established due to the absence of clinical trials. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
YK-11 is an unapproved research chemical and not for human consumption. It is not regulated by bodies like the FDA or EMA, meaning its quality, purity, and dosage consistency are not guaranteed. Individuals considering its use face significant risks due to the lack of clinical safety data. Specific warnings include:
* **Lack of Human Safety Data:** The most crucial warning is the absence of comprehensive human clinical trials. The long-term effects, full side effect profile, and potential interactions with medications or pre-existing health conditions are unknown.
* **Potential for Liver Toxicity:** As with many unregulated compounds and some SARMs, there is a theoretical risk of hepatotoxicity. Users should be aware of the signs of liver issues, although this is preventative advice for a compound not intended for human use.
* **Hormonal Suppression:** Use of YK-11 may lead to suppression of natural hormone production, particularly testosterone. This can cause significant side effects and may require medical intervention.
* **Cardiovascular Risks:** Although not specifically studied for YK-11, some SARMs have been associated with adverse changes in lipid profiles, potentially increasing cardiovascular risk. Individuals with pre-existing cardiovascular conditions or risk factors should be particularly cautious.
* **Adulteration and Impurity:** Products sold as YK-11 online may be impure, mislabeled, or adulterated with other substances, including prohormones or anabolic steroids, which carry their own unique and often more severe risks. The actual contents may differ significantly from what is advertised.
* **Legal Status:** Its legal status varies by region; generally, it is not approved for human sale and may be restricted as a research chemical. Its use in competitive sports is banned by anti-doping agencies.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Due to the complete lack of human clinical trials and comprehensive safety data for YK-11, definitive contraindications cannot be fully established. However, based on its proposed mechanism of action as a selective androgen receptor modulator (SARM) and its steroidal backbone, along with the observed contraindications for similar compounds and anabolic agents, YK-11 would theoretically be contraindicated in the following populations:
* **Pregnant or Breastfeeding Individuals:** Hormonal compounds can have severe adverse effects on fetal development and infant health. There is no data on YK-11 safety during pregnancy or lactation.
* **Individuals Under 25 Years of Age:** The skeletal and endocrine systems are still developing during adolescence and early adulthood. Introducing exogenous hormonal compounds can disrupt natural development and lead to irreversible side effects.
* **Individuals with Pre-existing Liver Conditions:** Given the theoretical risk of hepatotoxicity associated with some SARMs and unregulated compounds, individuals with liver disease, impaired liver function, or a history of liver issues should avoid YK-11.
* **Individuals with Prostate Issues:** As an androgen receptor modulator, YK-11 could theoretically exacerbate prostate conditions such as benign prostatic hyperplasia (BPH) or prostate cancer, often sensitive to androgenic stimulation.
* **Individuals with Cardiovascular Disease:** Although not directly studied, hormonal agents can impact lipid profiles and cardiovascular health. Individuals with heart disease, high blood pressure, high cholesterol, or a history of stroke or heart attack would be at increased risk.
* **Individuals with Hormone-Sensitive Cancers:** Any history or current presence of cancers sensitive to hormones (e.g., breast cancer, prostate cancer) would be a strict contraindication.
* **Individuals with Kidney Disease:** Hormonal changes can impact kidney function, and the effects of YK-11 on compromised kidneys are unknown.
* **Individuals with Psychiatric Conditions:** Hormonal fluctuations can impact mood and mental health. Individuals with depression, anxiety, or other mental health disorders may be more susceptible to adverse psychological effects.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any any compound.
Due to the extremely limited clinical data on YK-11, specific drug-to-drug interactions are largely unknown. However, based on its proposed mechanism of action as a partial androgen receptor modulator and its potential impact on hormonal systems, it is prudent to exercise extreme caution and avoid combining YK-11 with:
* **Other Hormonal Compounds or SARMs:** Combining YK-11 with other selective androgen receptor modulators, prohormones, or anabolic steroids would likely exacerbate the risk of hormonal suppression, liver strain, and cardiovascular side effects, and could lead to unpredictable interactions.
* **Liver-Toxic Medications or Supplements:** Given the theoretical concern for hepatotoxicity, combining YK-11 with other substances known to be processed heavily by the liver or that pose a risk of liver damage (e.g., certain antibiotics, antifungals, excessive alcohol, or some unregulated supplements) could increase the risk of liver injury.
* **Blood Thinners (Anticoagulants):** Any drastic hormonal shifts can sometimes influence coagulation factors. While not specifically documented for YK-11, it is generally ill-advised to mix unapproved compounds with anticoagulants without strict medical supervision.
* **Medications for Cardiovascular Conditions:** As hormonal changes can impact lipid profiles and blood pressure, combining YK-11 with medications for heart disease, high blood pressure, or high cholesterol could lead to adverse interactions and complicate treatment.
* **Supplements or Medications Affecting the Endocrine System:** Any compounds that influence hormone levels (e.g., thyroid medications, fertility treatments) could interact with YK-11 in unpredictable and potentially harmful ways.
* **Insulin or Oral Hypoglycemic Agents:** Any compound that affects muscle metabolism or body composition can theoretically impact insulin sensitivity or glucose utilization. Combining with diabetes medications without medical guidance could be dangerous.
This list is not exhaustive due to the lack of research. The safest approach is to avoid combining YK-11 with any other medications or supplements. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
YK-11's half-life is estimated to be approximately 10 hours. This relatively short half-life suggests that, if it were to be clinically used, it would likely be administered daily or potentially in divided doses (e.g., twice daily) to maintain stable blood levels. The typical route of administration seen in research contexts is oral, and it can be taken with or without food. However, due to its unapproved status and the lack of human data, specific recommendations for timing or administration frequency are based on general pharmacokinetic principles and anecdotal reports, not established medical guidelines. Any consideration of specific timing or dosage frequency is entirely hypothetical in the absence of clinical trials.
Source for this section: Sources for When should you take YK-11?: Jumps to this entry in the sources and references list at the end of the page.
What interacts with YK-11?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any peptide + hormone | Note | Category ruleConfidence: theoretical | Injectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pending | Track bloodwork with a provider; don't assume combinations are neutral. |
Frequently asked questions about YK-11
YK-11 is a synthetic investigational compound classified as a selective androgen receptor modulator (SARM) with a steroidal structure. It is proposed to act as a partial agonist of the androgen receptor and is uniquely hypothesized to inhibit myostatin, a protein that limits muscle growth, by increasing follistatin expression.
While YK-11 has a steroidal backbone, it is typically categorized as a SARM due to its proposed selective activation of androgen receptors. However, its structure does differentiate it from many non-steroidal SARMs. It is not an anabolic steroid in the traditional sense, but its effects share some similarities with anabolic agents.
Based on preliminary in vitro (cell culture) studies and anecdotal reports, YK-11 is primarily associated with potential increases in muscle mass and strength, largely attributed to its hypothesized myostatin-inhibiting properties. These benefits are not scientifically proven in humans.
Due to limited human research, the full side effect profile is unknown. Potential side effects speculated from its SARM activity and anecdotal reports include liver toxicity, testosterone suppression, cardiovascular strain (e.g., altered lipid profiles), and possibly androgenic effects like acne or hair loss. All usage carries significant unknown risks.
No. YK-11 is an unapproved research chemical and is not considered safe for human use. It has not undergone rigorous clinical trials to establish its safety, efficacy, or appropriate dosing in humans. Its sale and use for human consumption are not regulated, leading to concerns about product purity and undisclosed risks.
Interaction risk for YK-11 comes from the rest of the stack: other hormones, prescription medicines, hormone therapy and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers YK-11 with no sign-up.
Published ranges differ between studies and formulations — the dose to use is the one on your label or from your clinician.
There is no single answer for YK-11 plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing YK-11 with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for YK-11 varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of YK-11 depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For YK-11 the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at YK-11?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Detection of SARMs in doping control analysis(opens PubMed in a new tab)Mol Cell Endocrinol · 2018 · PMID 28137616 · https://pubmed.ncbi.nlm.nih.gov/28137616/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 119058028(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/119058028
Verify at
Publisher search links for YK-11. These are places to check the information — they are not citations, so they are not numbered.
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- DailyMed labeling archive(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on YK-11?
Plain-text summary, safe to quote verbatim:
YK-11, also known by its aliases Myostatin SARM or Myostatin-inhibiting SARM, is a synthetic investigative compound classified as a selective androgen receptor modulator (SARM). Research on YK-11 focuses on muscle and strength and testosterone support. Dose, response, and interaction risk vary by individual, so use should be reviewed with a clinician.
Source: DoseRoutine — https://doseroutine.com/library/yk-11
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). YK-11 — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/yk-11
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Which goals is YK-11 used for?
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