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S23 Comprehensive Guide | Benefits, Side Effects, Usage, PCT


S23 is one of the most powerful SARMs available today. It’s most commonly used for cutting cycles to prep for photoshoots, events, and even amateur bodybuilding shows.

It’s incredibly effective at retaining and even building muscle on a caloric deficit.

This article is a comprehensive guide on S23 based on the currently available scientific literature, and the analysis of hundreds of anecdotal reports and experiences. You will learn:

  • What is S23
  • Benefits
  • Side Effects
  • Dosing & Cycling
  • Stacking

What is S23?

S-23 is perhaps one of my most interesting SARMs on the market today.

It was developed by GTx, the same company that developed Ostarine and Andarine,  but unlike the other two it wasn’t developed for treating muscle-wasting conditions or osteoporosis.

The chemical formula for the SARM S-23

It was created as a possible type of male oral contraception. We don’t have any scientific data on the effects of S-23 on humans because it never made it to clinical trials.

S-23 is probably the strongest cutting SARM available today. Although initially highly promising and appealing on paper, it is gradually becoming less and less popular as users are neglecting it and choosing other SARMs and oral ASS instead.


Muscle Building

It is hard to measure exactly how much muscle you will gain using S-23 since it is rarely used in bulking cycles. People who use it on small calorie deficits report a significant gain in muscle mass.

Still, the limited anecdotal evidence I’ve seen about S-23’s use during bulking cycles suggests that it’s very anabolic and equivalent to SARMs like Ligandrol and Testolone in terms of lean muscle gain.

Strength and Performance

The anecdotal evidence we have concerning S-23’s performance-enhancing advantages is quite inconsistent and contradictory. On the one hand, whether they’re bulking up or losing fat, users are seeing a considerable gain in muscle mass and performance.

On the other hand, some users report a significant reduction in strength and performance after cutting, partially owing to S-23’s harshness on joints and partly due to the purported ability of S-23 to swiftly burn up glycogen, leaving users feeling tired and appearing very flat.

Fat Loss

S-23 has been shown to burn fat (dose dependant) in animal studies. Unfortunately, we have no way of knowing or confirming that this is also applicable to humans, however many users believe that S-23 boosts fat reduction anyways. 

Bones and Joints

S-23 will increase the strength and density of your bones. Unfortunately, it has a tendency to abuse joints and tendons, making users more susceptible to injury.


Like any of the other SARMs, S-23 too will speed up your recovery. You will be less sore, and able to train the same muscles sooner and harder than last time.


This is the part where S-23 truly shines, and the main reason why people still take it despite the risks and is the uncertainty involved. From anecdotal data, we can conclude that the cosmetic benefits are comparable to those of steroids like Masteron and Winstrol. 

S-23 will give you an extremely dry, hard, and vascular look. The downside is that it will also make you look really flat due to the lack of carbs in your muscles, so it will jeopardize the appearance of users who want to seem full and big.

Other Benefits

The contraceptive properties of S-23 is for some people a benefit while for others dangerous side-effect. I will touch up more on this property in the side-effects part of this article.

Side Effects

Testicular Shutdown

All SARMs cause testosterone suppression to an extent, but if taken in high enough doses for long periods of time they can all potentially cause a testicular shutdown. S-23 will cause testicular shutdown taken at any dose for any period of time.

It makes sense considering it was developed as oral contraception, and dropping LH and FSH levels to an absolute 0 is required to achieve that. Keep in mind that S-23 will not, in most situations, induce infertility on its own.

Testosterone suppression or shutdown will result in:

  • Testicular pain
  • Testicular atrophy
  • Lethargy
  • Lack of motivation
  • Irritability
  • Weaker erections (or complete erectile dysfunction)
  • Decreased libido

Unless you do a testosterone base, you will have every single one of these ruin your life for the duration of your cycle, until you do post cycle therapy.

S-23 will also decrease your SHBG, and lead to an increase in free testosterone which will improve your overall well-being in the first few weeks of your cycle. But only if you are using a test base.


S-23 will destroy your lipid panel. Even though all SARMs cause dyslipidemia, S-23, in particular, is a lot harsher than the rest, your HDL cholesterol will drop significantly and your LDL cholesterol will go to the moon.

You have to do bloodwork at the end of your cycle to measure the damage caused since this side-effect doesn’t manifest by impacting how you feel day to day.

Liver Toxicity

There is no scientific evidence showing that S23 is liver toxic, though, anecdotal reports consistently reveal a large rise in liver enzyme levels.

Androgenic Side Effects

Technically S-23 should not be androgenic, however, there have been hundreds of reports from users that experienced androgenic side effects like hair loss, acne, and aggression.

So it is safe to conclude that S-23 does possess androgenic side effects, although it’s still unclear why.

Increased Body Temperature

Some people experience increased body temperature. Excessive sweating, cramps, night sweats, and dehydration can easily happen as a result.

Other Side Effects

These side-effects only happen to a very small percentage of people.

  • Gynecomastia: The growth of breast tissue in males. An extremely rare side-effect which is caused by an imbalance in testosterone and estrongen. Men who developed pubertal gynecomastia are at greater risk of developing it if they take S-23
  • Insomnia: This side-effect is pretty random and only some people experience it, although it can be mitigated and dealt with easily.

SARMs have varied effects on different people. During an S-23 cycle, your friend may become impotent and infertile, while you impregnate your girlfriend with triplets.


S23 should be dosed between 10-30 mg/day.

This dose range has been shown to be the most effective across anecdotal reports. Anything higher and you will most likely experience diminishing returns and a disproportionate increase in side effects to benefits.

The half-life of S23 is unknown. So to achieve stable levels it’s best to split your dose and take it on three different occasions throughout the day.

Cycles should be kept from 4 to 8 weeks long. 

  1. Because S23 is harsh on your organs
  2. Because at the 8th week mark the build-up of myostatin becomes too great to continue making steady progress – you will most likely plateau.

Cycle Cheatsheet

Stacking S23

Many users go down the rabbit hole of stacking SARMs and end up with Frankenstein cycles that lead to a LOT of side effects, and sub-par gains in comparison.

One of the principles I preach when it comes to stacking SARMs is creating synergy.

When you stack SARMs that have a similar mechanism of action (that act on the same pathway) you end up with the two compounds fighting over the same receptors. 

My theory is that when this happens, the compound with the higher binding affinity wins – and kicks the other one out of the receptor making it completely useless.

Even though there is no “scientific evidence” to say that this is the case for sure, there is more than enough anecdotal evidence of users that stacked similar SARMs like Rad 140 and LGD 4033 and ended up with much harsher sides and suppression and only a minuscule increase in muscle and strength compared to just running one of the two.

S23 Rad 140 Stack

S23 is one of those SARMs that everybody wants to throw in their cutting cycle. Users most often stack it with other dry compounds like Rad 140 and S4.

Stacking Rad 140 with S23 is sub-optimal, and far less effective compared to stacking either one with YK11 or MK677 or even taking either one at a higher dose.

What to Stack S23 With

S23 works by attaching to a selection of androgen receptors in your body – androgenic pathway.

YK11 works by inhibiting myostatin and promoting follistatin production – myostatin pathway.

MK677 works by promoting IGF-1 and GH production – growth hormone pathway.

Combining compounds that act separately from one another in a synergistic way will ultimately bring you an incredible benefit-to-side effect ratio.

So only stack S23 with YK11, Cardarine, Stenabolic, and MK677.


S23 is an extremely strong cutting agent capable of adding a serious amount of muscle. It is best used for cutting as it’s a very dry compound and will bring out the best in your physique for when you need it.

It should not be taken lightly though. Doing a test base and PCT are absolutely mandatory if you want to have a productive cycle, and keep your health in check.

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