STUDresearch · Non-peptide
S-23
Also known as
S23 · S 23 · S-23 · S-23 SARM · S23 SARM · Mastorin (informal / research-chem trade discussion) · Ultrabolic (branded research-chem label discussed in forums) · (S)-N-(4-cyano-3-trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methylpropanamide · s23
Community talk. May be wrong. Not medical advice. Not a protocol. Not for human or animal use.
Non-peptide
Some talk
Systemic
Oral
Performance / endurance
Systemic SARM research chem.
What people say
S-23 is an unapproved nonsteroidal SARM discussed for aggressive recomp and suppression. Its contraceptive and PK evidence is preclinical, not a human use standard.
Doses people talk about
These are unverified self-reports, not a progression or clinical regimen. Product identity and multi-agent stacks prevent clean dose-response conclusions.
How it may feel
Oral reports mention pumps, strength, libido or appearance changes, but also insomnia, anger and hair loss. Testosterone, HCG, other SARMs and Anadrol confounded the detailed accounts.
Broad community band~10–30 mg/day oral
The preserved range is highly variable and does not establish safety, product accuracy or a preferred schedule.
Four-week split account20 mg/day oral, split morning and evening
One author used this for four weeks after eight weeks of RAD-140 and with HCG throughout; claimed outcomes cannot isolate S-23.
Side-limited account20–25 mg/day oral; separate 30–40 mg/day attempts
The author also used testosterone and, at points, Anadrol; insomnia, hair loss and mood effects led to ending the planned near-eight-week period early.
Half-life & effect duration
- Half-life in the body
- Oral · ratsAbout 11.9 hours
- IV · ratsAbout 10.9 hours
- Felt duration people report
- Early accountPumps around days 3–4
- Longer stacked-use accountsDesired and adverse changes across 4–8-week runs
Cycles people discuss
The notes describe short cycles and PCT lore; inspected accounts ran S-23 for about four weeks or planned nearly eight. Those are reports, not an established calendar, and stop decisions were side- or goal-dependent.
Timing
Forum charts often split the oral daily total, but human parent pharmacokinetics are not established. The roughly 11.9-hour oral half-life comes from male rats at 10 mg/kg, not people.
Stacks
YK-11 and larger multi-agent stacks appear in S-23 discussion. Those combinations increase risk and make personal attribution weaker; the preserved solo-run note is an interpretation aid, not a use recommendation.
Watch for
Suppression: Strong HPTA suppression narratives.
Tap a line to jump into the full notes. Research only — may be wrong.
Timing context & sources
Half-life in the body
No dependable human parent half-life was located.
A preclinical study reported an 11.9-hour oral half-life after 10 mg/kg in male rats, with 10.9 hours after intravenous dosing and 96% oral bioavailability. It cannot be converted into human timing.
Rat dose, species and contraception model; no human therapeutic or gray-market formulation pharmacokinetics.
- Jones et al. (2009): S-23 pharmacokinetics and hormonal male contraception in rats (opens in a new tab)PubMed abstract plus indexed full-text methods/results reviewed: male Sprague-Dawley rat 10 mg/kg oral and IV PK; oral and IV half-lives, bioavailability and contraception study context.Animal-only evidence; no human parent PK or approved use. Direct PMC page returned a browser verification page during review.
Felt duration people report
Reports do not establish a characteristic onset or felt-duration window.
One multi-author thread described pumps around days 3–4 at 10 mg/day, while detailed four- and near-eight-week accounts mixed S-23 with other anabolic agents and reported both desired and adverse changes.
Self-selected reports, unverified product identity, different daily totals and extensive co-exposure; no prevalence or causal timing can be inferred.
- What's your experience with SARM S23? (opens in a new tab)Multiple distinct authors reviewed: reported 10 mg/day split, 20–30 mg/day and higher-stack examples, with TRT, YK-11, Cardarine, tadalafil or tirzepatide appearing in different accounts; one described pumps around days 3–4.Multiple unrelated authors and protocols; unverified products, absent controls and incomplete labs; comments cannot be merged into one person's course.
- My experience with S23 with before and after (opens in a new tab)OP and visible same-author follow-ups reviewed: 20 mg/day split morning/evening for four weeks after eight weeks of RAD-140, with HCG throughout; claimed appearance, strength, aggression and libido effects plus later PCT context.Unverified product and outcomes, sequential/mixed cycle, HCG co-use, photos without controls, no clinical measurements; cannot isolate S-23.
- S23 cycle report ended early due to sides (opens in a new tab)OP and visible same-author clarifications reviewed: 20–25 mg/day during a planned near-eight-week period, with separate 30–40 mg/day attempts; testosterone throughout and brief Anadrol use; sleep, hair, mood, libido and strength claims.Unverified products, multiple dose changes and strong co-exposures; author was deleted; no labs or controlled attribution.
What people say
- Recomp talk: Strength and lean look anecdotes; confounded. anecdote
- Body-comp talk: S-23 is discussed for recomp, strength continuity, or soft-tissue recovery depending on class. forum
- Training confound: PRs and scale changes almost always co-travel with diet phase and programming. anecdote
- Suppression / lipid chatter: Hormonal agents pull bloodwork and PCT conversations even when marketed “mild.” forum
- Cycle thinking: Fixed on/off blocks dominate over indefinite daily use. forum
Doses people talk about
- Community bands: Often ~10–30 mg/day oral discussed — highly variable. forum
- Quality flag: Assume label accuracy only if analytically verified — gray market fill error is common. forum
- Product quality: Gray-market fill accuracy and identity are uncertain; dose math assumes the label is true. forum
- Route changes the math: Oral vs SC vs nasal are not interchangeable milligram-for-milligram stories. forum
- Start conservative (community): When people experiment, they often start at the low end of a charted band to gauge tolerance — still not advice. forum
- Framing: All figures are discussed trial, clinic, or community amounts — research/educational only, not prescriptions. forum
How it may feel
- Days 1–7: The inspected oral reports do not establish a uniform first-week feel. One multi-compound account described pumps by days 3–4 at 10 mg/day split; other reports emphasized later strength, libido, sleep, anger or hair effects under substantial co-exposure. forum
- Weeks 1–8: Actual posts described four-week and near-eight-week S-23 periods, but every detailed account inspected also involved testosterone, another SARM, HCG or other agents. Strength, appearance and adverse changes therefore cannot be assigned to S-23 alone. forum
- Day 1: No inspected account established a characteristic first-dose effect. Oral product identity, split schedules and extensive co-exposures make early attribution especially weak. forum
- Days 2–7: Side-effect window for many agents; benefits, if any, are easy to mis-attribute. forum
- Weeks 1–2: First honest checkpoint in self-logs. forum
Cycles people discuss
- Length: Short cycles + PCT lore common. forum
- Common pattern: Many self-protocols use weeks-on / weeks-off rather than indefinite daily use — cost and caution drive this more than hard science. forum
- No magic cycle: There is rarely one universal “correct” on/off calendar across forums. forum
- Reassess: Stop and reassess if adverse effects appear; this is not medical care. forum
Timing
- Dosing frequency: Often split daily in charts. forum
- Timing practicalities: People time doses around side effects, training, and sleep more than perfect PK. forum
- Published PK: Where human PK exists it should override forum half-life memes for S-23. trial
More on what it is
- Reputation: Forums call it one of the harsher SARMs — recomp + suppression stories. forum
- What it is: Nonsteroidal SARM research chem discussed for aggressive recomp and high suppression potential. forum
- Reputation: Often labeled “harsh” relative to Ostarine in forums. forum
- Research posture: Educational summary of public discussion and literature themes only. forum
- How people talk about it: Forum volume is a popularity signal for S-23, not proof it works for you. forum
- Research only: Not approved advice for self-experimentation; legality and access vary by place. forum
Stacks
- With YK-11: Sometimes stacked — risk stacking. forum
- Less is clearer: Solo runs make personal n=1 easier to interpret than five-compound blasts. forum
Storage notes
- No mix instructions here: STUDresearch does not list reconstitution, diluent volumes, or syringe unit charts. People reconstitute many different ways and vial labels differ — that content creates more confusion than clarity. forum
- Storage (general talk only): Unopened research products are usually kept cool, dry, and away from light per the seller label. Anything after first use is product-specific — follow the label, not a universal forum SOP. forum
Watch for
- Suppression: Strong HPTA suppression narratives. forum
- Lipids / aggression: Community cautions. forum
- Oral gray-market identity: The inspected accounts relied on labeled research products, not verified clinical S-23. Reported sleep, mood, libido, hair and suppression changes remain product- and stack-confounded. forum
- Unknowns: Long-term safety for gray-market preparations is often poorly characterized. forum
- Stack noise: Sides logged on multi-agent stacks cannot be blamed cleanly on one compound. forum
- Seek care red flags: Severe allergic reaction, chest pain, neuro changes, or uncontrolled BP/glucose need real medical care — not forum advice. forum
- Unapproved-drug status: SARMs are not FDA-approved for human use and are not legal dietary-supplement ingredients. This card maps forum talk only — not a sourcing guide, not a safety claim, and not a promise of results. trial
Evidence mix
Mostly community / anecdote tags
Full: every bullet (trial + community). Use Scan for a faster bro-science read.