Many users think YK11 is the key to achieving fast muscle gains with few side effects. YK11 is promoted as a super-SARM, but this drug is NOT a typical SARM. This article breaks down the science and reviews to give you a clear idea of what to expect from YK11, with risks and side effects.

Disclaimer: By writing this post, we are not recommending this drug. Some of our readers who were already taking the drug requested that we commission a post on it, and we are simply providing information that is available in the clinical and scientific literature. YK11 is specifically a drug that we at SelfHacked would recommend against.

What is YK11?

Steroid-SARM Hybrid

YK11 is a new synthetic steroid based on 5-α-dihydrotestosterone (DHT), a hormone naturally found in the human body. DHT is a stronger form of testosterone that targets androgen receptors in the prostate, sex organs, hair, and liver.

YK11 is gaining interest from bodybuilders due to its ability to quickly build muscle with minimal side effects, much like various SARMs. The YK molecule has more in common with steroids than SARMs, although it’s often mistakenly labeled as a non-steroidal SARM [1].

According to preliminary cell studies, YK11 may increase muscle mass and enhance bone health [2, 3].

Some bodybuilders who have experimented with YK11 report great muscle gains and fat loss with minimal side effects. However, there are currently no animal or human studies of YK11 and its safety profile is unclear.

Along with all steroids and SARMs, YK11 is banned in professional sports by the World Anti-Doping Agency [4].

YK11 is a synthetic steroid with SARM properties, promoted to quickly build muscles with minimal side effects. It’s banned in professional sports and not well researched yet.



  • Increases muscle growth
  • May boost fat-burning
  • May increase bone strength
  • May be safer than steroids


  • Steroidal structure (not a typical SARM)
  • Testosterone suppression
  • No human or animal studies
  • Long-term risks unknown

Is It a SARM?

Bodybuilders and researchers sometimes refer to YK11 as a SARM (selective androgen receptor modulator). This may be misleading as other SARMs differ from YK11.

YK11 is a steroid made by altering the chemical structure of DHT. In contrast, all other SARMs have a nonsteroidal structure. YK11 and SARMs work differently in the body and may have different side effects [1, 5].

Cell studies do show that YK11 has a selective effect on androgen receptors. This means the SARM label does technically describe YK11 [1].

Because this class of drugs is new, no established naming convention exists.

Based on its activity and chemical structure, it may be more appropriate to call YK11 a synthetic steroid rather than a SARM.

How Does It Work?

The chemical structure of YK11 is similar to DHT, and it binds to androgen receptors in a similar way. DHT is a naturally occurring hormone in the body crucial for hair growth, prostate health, and proper development in puberty.

Some bodybuilding resources state that YK11 is one of the strongest SARMs on the market. However, research revealed that YK11 only partially activates androgen receptors. Such limited activation increases the activity of catabolic (muscle-degrading) genes [1].

A recent cell study uncovered YK’s unique muscle-building mechanism: increasing follistatin levels. Follistatin is a naturally occurring protein in that suppresses myostatin, which otherwise prevents muscles from getting too large. In comparison, no other SARMs show myostatin inhibition [2].

YK11 may also increase bone growth by affecting a DHT-like pathway, according to other cellular studies [3].

YK11 works by mimicking DHT and activating androgen receptors in muscles and bones; it also inhibits myostatin by increasing follistatin.

Potential Uses of YK11

1) May Increase Muscle Size

According to cell-based studies, YK11 boosts muscle growth by increasing follistatin levels and thus inhibiting myostatin [2].

YK11 has not been studied in animals or humans.

Anecdotal evidence from bodybuilders suggests it is effective at increasing muscle size. Users report lean muscle gains of up to 15 lbs. and a decrease in body fat after a single cycle.

YK11 may boost muscle growth by inhibiting myostatin. There are no human or animal studies to confirm this, but bodybuilders report lean muscle gains and fat loss.

2) May Strengthen Bones

Sex hormones play an important role in maintaining healthy bones. YK11 may be able to bind to androgen receptors in bone tissues and increase bone strength, similar to steroids and SARMs.

YK11 increased levels of activated PKB (protein kinase B) in cells; activated PKB sends signals to increase bone growth [3].

Thanks to its muscle-building effects, YK11 may also support bone health, similar to SARMs. This would be especially relevant in older people who struggle with both muscle and bone frailty [6].

YK11 may strengthen the bones by activating androgen receptors and protein kinase B. Its muscle-building effects may help prevent fractures, especially in the elderly.

YK11 for Bodybuilding

User Reports

New SARMs are always a hot bodybuilding topic, as they promise to increase muscle mass and burn fat with minimal side effects.

Positive reviews of YK11 report that it greatly increases muscle mass in as little as a week. However, these claims are clouded by the fact that people use different dosages, cycle lengths, or stack YK11 with other SARMs.

Some state that YK11 offers similar results to other SARMs. Many would prefer taking a SARM that is backed up with better research than YK11 if the results are similar.

Bodybuilders have experimented with YK11 in both bulking and cutting. Allegedly, it works great both ways by building lean muscle mass and burning fat.

All these claims remain purely anecdotal. Users must be cautious as the information on YK11’s safety and long-term effects is scarce.

Bodybuilders tout YK11 as a relatively safe option for building lean muscles and burning fat, but studies are lacking to support these claims.


Anecdotal reports suggest the most common dosage is 10-15 mg, divided into two daily doses. Users have also seen good effects at 5 mg, which is a recommended starting dose for new users. Some people report doses as high as 30 mg with no side effects. It is usually cycled for 4 to 8 weeks.

Women report taking 0.5-2 mg per day.

Most users take YK11 by mouth while some have used muscle injections.

Anecdotal evidence suggests that stacking YK11 with other SARMs can lead to superior results. Users report stacking with LGD-4033 or RAD140 and using a lower dose of YK11, typically 5-10 mg per day.

Most users take 10-15 mg of YK11 per day, divided into two doses. Some stack it with other SARMs and use lower doses. Women usually take 0.5-2 mg/day.

In Professional Sports

Anabolic agents, including all SARMs, are prohibited in professional sports by the World Anti-Doping Agency. No matter how YK11 is labeled – as a SARM or synthetic steroid – it is banned in competitions [4].

The doping test is currently in use and can detect YK11 metabolites up to 2 days after use [7].

Limitations and Caveats

The current research on YK11 is scant. It has not been studied in animals or humans. All cellular studies on YK11 have been done by one group of researchers from Japan.

YK11’s safety and effectiveness can only be evaluated once more research is done.

Side Effects

Unknown Safety

YK11 has only been studied in cells so far. There’s no clinical information on side effects. Not even animal studies have been carried out yet.

In a cell study, YK11 increased the levels of follistatin. High follistatin may increase the risk of esophagus, stomach, skin, and prostate cancer. On the other hand, a human study suggests it may be beneficial for breast cancer [8, 9, 101112].

The chemical structure of YK11 is very similar to other steroids that are toxic to the liver. YK11 may have toxic effects on the liver as well [13].

Theoretically, it may also affect the prostate, hair growth, vocal cords, and other organs.

No clinical or animal trials have examined the safety of YK11. It increases follistatin, which may raise the risk of certain cancers. Other steroid-like side effects are possible.

Beyond the Science

Given the limited research, information from the bodybuilding community gives more insight into the potential real-world side effects of YK11. These include:

  • Increased aggression
  • Joint pain
  • Low energy
  • Mild testosterone suppression
  • Hair loss
  • Mild acne

YK11 is potentially toxic to the liver. However, some users reported doing blood tests during cycles of YK11, and initial results didn’t indicate abnormal markers of liver damage.

Mild testosterone suppression is possible. To be on the safe side, almost all bodybuilding resources recommend post-cycle therapy (PCT) after a cycle of YK11. Common PCTs include Nolvadex (tamoxifen) and Clomid (clomifene).

Bodybuilders have reported side effects such as aggression, joint pain, fatigue, hair loss, and testosterone suppression. Most resources recommend PCT after each YK11 cycle.

Buy YK11

There are vendors who sell YK-11 in the United States. You can get 10% off by typing in the code “selfhacked”.

This section contains a sponsored link, which means that we may receive a small percentage of profit from your purchase, while the price remains the same to you. The proceeds from your purchase support our research and work. Thank you for your support.

We at SelfHacked advise speaking to a doctor before taking any drug, especially an unscheduled drug with limited long-term safety data in humans.


YK11 is a new steroid-SARM hybrid. It has a steroid structure and the selectivity of non-steroidal SARMs. So far, only cell-based studies confirmed it can build muscles via myostatin inhibition.

Users report major gains for bulking and cutting cycles (4-8 weeks) that few other SARMs can par with. On the downside, YK11 may cause testosterone suppression, joint pain, and hair loss. According to most experienced users, PCT is a must.

Despite its promising effects, both animal and human studies are needed to determine the safety and effects of YK11.

About the Author

Mathew Eng, PharmD


Mathew received his PharmD from the University of Hawaii and an undergraduate degree in Biology from the University of Washington.

Mathew is a licensed pharmacist with clinical experience in oncology, infectious disease, and diabetes management. He has a passion for personalized patient care and believes that education is essential to living a healthy life. His goal is to motivate individuals to find ways to manage their chronic conditions.

Click here to subscribe


1 Star2 Stars3 Stars4 Stars5 Stars
(45 votes, average: 4.04 out of 5)

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.