SARMs & Related Compounds
S-23
C-SARM · S23 · steroidal compound
What it is
S-23 is an experimental steroidal SARM that never made it past preclinical development. It's a potent androgen receptor agonist with dual effects: anabolic in muscle and bone, but crucially, it's antagonistic in the prostate (makes it shrink). Developed for male contraception and prostate disease. Extremely niche; availability is spotty.
How it works
Tissue-selective androgen receptor agonism with antagonism in the prostate. The anabolic/catabolic selectivity varies by tissue. Originally explored as a male contraceptive because it suppresses sperm production while building muscle.
Benefits
- Significant lean mass gains (steroid-like)
- Prostate shrinkage (unique among SARMs/androgens)
- Strength gains
- Aggression/drive increase
Timeline
- Week 1–3
- Strength gains; aggression ramp.
- Week 4–8
- Visible muscle gains; prostate effects.
- Week 8–12
- Peak; cycle off mandatory; strict PCT required.
Dosing & titration
Beginner dose5–10 mg orally daily
Standard dose10–25 mg orally daily
Cycle length8–12 weeks ON, then 8–12 weeks OFF (with strict PCT)
When to titrate upAbove 25 mg, azoospermia (no sperm) becomes permanent. Most users stay 10–20 mg.
Side effects & risks
- Aggressive testosterone suppression (azoospermia risk above 20 mg)
- HDL reduction (severe in some users)
- Liver toxicity (methylated structure)
- Aggression/anxiety
- Potential fertility issues at higher doses
- Joint dryness
Fertility risk — treat seriously. Azoospermia is reversible but can take months. Baseline semen analysis recommended before cycle. Strict PCT post-cycle. Not for users planning fertility in the next 12 months. Banned in sports. No human trials completed.
Typical price
$80–$150/moExtremely hard to find. Quality/purity unknown.
Studies
- Dalton JT et al. Preclinical and clinical pharmacology of a selective androgen receptor modulator candidate for male contraception — Early S-23 research. PubMedSearch PubMed directly for S-23 studies
Educational reference only. Not medical advice. Not FDA-approved.