Lower numbers = closer to natural. Higher numbers = more enhanced.
Why this rating?
S-23 is considered the most potent SARM, binding to androgen receptors with very high affinity similar to anabolic steroids. It was researched as a male contraceptive because it causes complete testosterone shutdown, requiring a testosterone base and aggressive PCT. The steroid-like results, night sweats, and aggression mirror actual steroid use. Rated 6: the strongest of the SARMs and near steroid-like in suppression, but still a SARM and kept below testosterone (7).
Overview
Considered the most potent SARM, often yielding results comparable to steroids. Provides extreme muscle hardening and strength with complete testosterone shutdown.
Important Warnings
- •Causes complete (contraceptive-grade) testosterone shutdown - human recovery not guaranteed without aggressive PCT
- •Should only be used with a testosterone base
- •Most androgenic common SARM - high hair-loss and lipid risk; finasteride does NOT help SARM hair loss
- •More side effects than other SARMs (night sweats, aggression)
- •Approaching or exceeding steroid-level suppression
- •Not approved for human use; very limited human data
Purpose & Use Cases
Muscle Hardening
Provides steroid-like hardening and dryness to muscle.
Strength Gains
Significant strength increases comparable to mild steroids.
Lean Mass
Builds quality lean muscle without water retention.
Benefits
- Steroid-like results
- Extreme muscle hardening
- Significant strength gains
- Enhanced fat loss
- Improved vascularity
- No water retention
Good to Know
Researched as a male contraceptive: it causes complete, reversible shutdown
S-23 produced complete, reversible suppression of spermatogenesis in animal studies (it was investigated for hormonal male contraception). In practice that means near-total HPTA shutdown: expect zero natural testosterone during use. Fertility and axis function recovered after cessation in the animal work, but in humans that recovery is not guaranteed without an aggressive, well-run PCT.
Effectively a steroid: run a testosterone base
Because S-23 shuts the axis down completely, running it "solo" leaves you with crushing low-testosterone symptoms (libido loss, lethargy, mood). Users therefore run a testosterone base, which pushes S-23 firmly into steroid-cycle territory in terms of suppression, PCT intensity and bloodwork needs, not "just a SARM."
Most androgenic of the common SARMs: high hair and lipid risk
S-23's high receptor affinity makes it the most likely of the popular SARMs to accelerate hair loss and hammer lipids. As always with SARMs, finasteride cannot help the hair loss (no DHT-conversion step). Night sweats and aggression are also commonly reported.
Gains behave like any androgen cycle
The dry, hard look and strength are real, but a portion is water/glycogen that leaves on cessation, and holding muscle depends entirely on recovering endogenous testosterone. Myonuclei added while training persist (muscle memory), modestly raising your future re-gain ceiling, but not letting you keep peak-cycle mass indefinitely.
Dosage Guidelines
| Experience Level | Dosage Range |
|---|---|
| Beginner | 10 – 10 mg/day |
| Intermediate | 10 – 20 mg/day |
| Advanced | 20 – 30 mg/day |
ALWAYS use with a testosterone base due to complete shutdown.
Community/vendor estimate: S-23 was never in human trials, so no formal published human pharmacokinetic study establishes this precisely.
Side Effects
Complete Testosterone Shutdown
very commonCauses complete suppression of natural testosterone production.
Always use with testosterone base. Aggressive PCT required.
Aggression
commonIncreased aggression and irritability.
Monitor mood; reduce dose if needed.
Night Sweats
commonSweating during sleep.
Keep room cool; manageable for most.
General Mitigation Strategies
Testosterone base is essentially mandatory to prevent severe low-T symptoms. Aggressive PCT required. This is closer to a steroid than a typical SARM.
Support Supplements
Ancillary supplements commonly run alongside S-23 to manage side effects, support the target tissue, or fill nutrient demands it creates.
Lipid support (omega-3 + citrus bergamot)
KeyS-23 is the most androgenic common SARM and hits HDL hard. Omega-3 supports triglycerides; citrus bergamot helps LDL.
- Dose
- Omega-3 2-4 g/day; citrus bergamot 500-1,000 mg/day
- Timing
- With meals
- When
- Lipid strain is amplified because S-23 is almost always run with a testosterone base, monitor a full panel.
Post Cycle Therapy (PCT)
Rigorous PCT required. Consider HCG during cycle. Full SERM protocol (Nolvadex or Clomid) necessary.
How It Works
S-23 binds to androgen receptors with very high affinity (Ki approximately 1.7 nM), stronger than earlier-generation SARMs like andarine (S-4) and approaching steroid-level affinity. In rat studies (combined with estradiol benzoate) it produced complete, reversible suppression of spermatogenesis and LH/FSH, which is why it was investigated as a potential male contraceptive. Provides strong anabolic effects with significant androgenic activity.
Hormonal & Androgenic Profile
Very high androgen-receptor binding affinity approaching steroids, researched as a male contraceptive precisely because it shuts down the axis completely.
S-23 itself does not aromatize, but it is almost always run with a testosterone base, so an AI may still be needed to manage estrogen from the testosterone, not from the S-23.
Not a 5-alpha-reductase substrate; finasteride/dutasteride do not blunt its androgenic hair/prostate effects, which come from direct receptor activation. S-23 is androgenic enough that hair-loss risk is high in predisposed men.
Strong HDL suppression and lipid strain typical of a potent androgen, compounded by the near-obligatory testosterone base. Treat cardiovascularly like a steroid stack.
Fundamentals
Reference on the practices relevant to S-23: how they are done and where they go wrong. Not a recommendation to use it.
Legal Status
Sold in the USA as a research chemical, not for human consumption.
Legal status varies by country and changes over time. This is a general summary, not legal advice.
WADA Status
S-23 is explicitly listed as a prohibited SARM under S1.2 Other Anabolic Agents.