S23 SARM: Dosage, Half Life, Results, Side Effects, and PCT
Summary:
S23 is one of the most powerful Selective Androgen Receptor Modulators (SARMs) known in bodybuilding circles. This advanced guide covers the S23 dosage, S23 half-life, mechanism of action, results, suppression, S23 side effects, and post-cycle therapy (PCT) needed for safe use.
What Is S23?
S23 is a next-generation androgen receptor modulator originally developed for male contraception and lean muscle preservation. Its potency makes it one of the strongest SARMs available, often compared to RAD-140 (Testolone) and LGD-4033 (Ligandrol).
While originally designed to reduce fertility by suppressing testosterone, its anabolic strength quickly made it popular among advanced bodybuilders seeking rapid recomposition, hardness, and extreme definition.
S23, chemically known as (2S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide, is a non-steroidal selective androgen receptor modulator (SARM) derived from the same lineage as S4 (Andarine). Structurally, it belongs to the aryl-propionamide class of SARMs, which were engineered to achieve high androgen receptor (AR) selectivity in skeletal muscle and bone tissue without the unwanted androgenic effects in the prostate and skin. Its design incorporates halogenated aromatic rings and a cyano group that enhance receptor binding affinity and metabolic stability, giving it one of the strongest AR binding constants among all known SARMs.
From a biochemical standpoint, S23’s molecular architecture enables tight AR binding with full agonist activity, unlike partial agonists such as S4 or LGD-4033. Its trifluoromethyl and nitrile substituents increase lipophilicity, improving cell membrane permeability and oral bioavailability. The inclusion of chlorine and fluorine atoms extends its metabolic half-life and resistance to enzymatic degradation, which helps maintain steady blood concentrations over 10–12 hours. These molecular enhancements make S23 a powerful compound—pharmacologically efficient in muscle anabolic signaling, but also notably suppressive to endogenous testosterone production due to its potency and complete receptor occupancy.
In short:
S23 binds tightly to androgen receptors in skeletal muscle, promoting lean mass while simultaneously suppressing natural testosterone production.
How S23 Works (Mechanism of Action)
S23 binds with exceptionally high affinity to androgen receptors (ARs) in muscle and bone tissue. Once activated, these receptors stimulate muscle protein synthesis and reduce muscle breakdown through proteasome inhibition.
Simplified breakdown:
- Androgen receptor activation: Enhances anabolic signaling in muscle and bone.
- Anti-catabolic effect: Protects muscle during caloric deficit.
- No aromatization: No estrogen-related water retention.
- Feedback suppression: Strong negative feedback on the hypothalamic-pituitary-gonadal (HPG) axis, lowering LH and FSH output.
The result is dry muscle hardness and strength increases that mimic anabolic steroids but with fewer androgenic side effects on the prostate and skin.
S23 Half Life and S23 Dosing Guidelines
S23 Half-life: Approximately 11 to 12 hours, which makes split dosing twice daily the most common practice among users.
User-reported dosing patterns:
| Experience Level | Total Daily Dose | Dosing Frequency | Cycle Duration | Notes |
|---|---|---|---|---|
| Beginner | 10 mg/day | 5 mg AM / 5 mg PM | 4-6 weeks | Used to gauge tolerance |
| Intermediate | 20 mg/day | 10 mg AM / 10 mg PM | 6-8 weeks | Most common working dose |
| Advanced | 30 mg/day | 15 mg AM / 15 mg PM | 4-6 weeks | High-end dose, risk of heavy suppression |
Important: Longer or higher-dose cycles exponentially increase suppression, making a proper PCT mandatory.
S23 Results: What to Expect
S23 is often referred to as a “stage-prep SARM” due to its extremely dry and vascular appearance. Most lifters report rapid strength increases, visible hardness, and fat loss when paired with proper diet and training.
Reported Benefits
| Goal | Result Reported by Users | Timeline |
|---|---|---|
| Muscle preservation during cutting | Strong retention, harder appearance | 2–3 weeks |
| Fat loss acceleration | Noticeable when in caloric deficit | 3–4 weeks |
| Strength increase | Rapid surge, particularly in compound lifts | 1–2 weeks |
| Muscle hardness & vascularity | Significantly improved | 2–3 weeks |
| Improved recovery | Faster between sets and sessions | Throughout cycle |
User feedback from Reddit and forums commonly describe S23 look as “grainy, dry, and dense”—similar to low-dose Winstrol or Masteron, but without water retention.
S23 Side Effects and Suppression
1. Testosterone Suppression
S23 is the most suppressive SARM currently known. LH and FSH often drop to near zero within 2–3 weeks of use. Libido, energy, and mood can crash after discontinuation if no PCT is applied.
2. Lipid Alterations
Expect HDL reduction and LDL elevation due to hepatic androgen signaling. Cardio and omega-3 supplementation are essential during cycles.
3. Mood and Sleep
Users frequently report night sweats and sleep disturbances due to elevated thermogenesis and increased CNS stimulation.
4. Hair and Skin
Mild androgenic activity may accelerate hair thinning in genetically predisposed individuals. Since S23 does not convert to DHT, this effect is less severe than with testosterone or DHT-based steroids but still possible.
5. Liver Enzymes and Blood Pressure
AST and ALT can rise in sensitive individuals. Monitor blood pressure, especially at higher doses.
S23 vs Other SARMs
| Compound | Primary Use | Strength | Suppression | Cosmetic Effect | Half Life | Beginner Friendly |
|---|---|---|---|---|---|---|
| S23 | Cutting / Recomp | Very High | Extreme | Dry / Grainy | ~12 hrs | No |
| RAD-140 | Lean Mass / Power | High | High | Lean / Full | ~24 hrs | Moderate |
| LGD-4033 | Mass Gain | Moderate | Moderate | Fuller / Softer | ~24-36 hrs | Yes |
| S4 (Andarine) | Cutting / Hardness | Moderate | Moderate | Dry / Vascular | ~6 hrs | Somewhat |
S23 sits in the RAD-140 class of potency, but is considered a hardcore compound best suited for advanced athletes familiar with PCT and suppression management.
Stacking S23: Advanced Use Cases
| Stack | Why It’s Used | Benefit | Caution |
|---|---|---|---|
| S23 + Cardarine (GW-501516) | Cutting and endurance | Enhanced fat loss, better cardio | Monitor lipids |
| S23 + RAD-140 | Strength + Density | Explosive strength and full hardness | Heavy suppression |
| S23 + MK-677 | Lean mass + sleep support | Preserves size during cut | Water retention risk |
| S23 + Low-dose Testosterone | Adds estradiol balance | Maintains libido, mood | Requires full-cycle monitoring |
Post-Cycle Therapy (PCT) After S23 Sarms
Because S23 can suppress endogenous testosterone almost entirely, a real PCT protocol is essential.
Typical PCT outline (example):
| Compound | Dose | Duration |
|---|---|---|
| Clomiphene (Clomid) | 50 mg/day | 4 weeks |
| or Tamoxifen (Nolvadex) | 40 mg/day | 4 weeks |
| Optional: hCG (if prescribed) | 250–500 IU EOD | 2–3 weeks |
| Support supplements | Zinc, D3, Omega-3, Ashwagandha | During and post cycle |
Labwork timeline:
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Pre-cycle: Baseline TT, FT, LH, FSH, Lipids, Liver enzymes
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Mid-cycle: Check suppression and enzyme stress
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Post-cycle (4–6 weeks): Confirm hormonal recovery
Safety and Legality
S23 is not approved for human use and is classified as a research chemical. It is banned by WADA and most competitive sports organizations. Purity varies across sources, making third-party testing critical.
If you are a tested athlete, any use of S23 SARM is grounds for suspension or disqualification.
S23 for Women: Risks and Warnings
S23 is not recommended for women. Even at microdoses (1–5 mg), virilization—voice deepening, menstrual disruption, and hair growth—can occur. Safer alternatives include MK-677 or Cardarine for recomp goals without androgenic risk.
Real-World Feedback (Forums and Social Media)
Across bodybuilding boards and Reddit communities:
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Many report impressive muscle density and fat loss with proper diet.
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Users often note zero estrogenic bloat.
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Nearly all mention heavy suppression after 4–6 weeks.
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Common PCT symptoms: fatigue, low libido, mood flattening (2–4 weeks).
The consensus: S23 works, but requires planning, discipline, and medical oversight.
S23 Pros and Cons Summary
| Pros | Cons |
|---|---|
| Significant muscle hardness | Severe suppression |
| Excellent for cutting | Not beginner friendly |
| Dry, aesthetic physique | Lipid imbalance |
| Fast strength increase | Night sweats, insomnia |
| No water retention | Requires strong PCT |
Key Takeaways
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S23 SARM is potent, precise, and unforgiving.
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Expect fast strength, hard muscle, and zero water.
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Prepare for severe testosterone suppression and plan PCT in advance.
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Not suited for beginners or recreational lifters.
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Use only under expert supervision with pre- and post-cycle labs.
FAQs
What is the half-life of S23?
S2 Half life is About 11 to 12 hours. Split doses twice daily for stable plasma levels.
What is the best dosage for S23?
Most users report S23 Dosage of 20 mg per day (10 mg AM / 10 mg PM) for 6–8 weeks.
Does S23 cause suppression?
Yes, S23 is the most suppressive SARM known. S23 PCT is essential.
Is S23 good for cutting?
Yes. It enhances muscle retention and hardness during caloric restriction.
Can women take S23?
Not recommended due to high virilization risk.
Is S23 legal?
No. It’s banned by WADA and not approved for human consumption.
