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hormoneNot FDA-approvedResearch chemicalNo FDA-approved product exists; S-23 is sold as an unregulated research chemical with no human trial data behind itDetected as a doping agent in equine, bovine and canine samples, which is the primary reason analytical labs have studied it

S-23Benefits, Dosage & Interactions

S-23 is an investigational non-steroidal selective androgen receptor modulator originally studied as a candidate male hormonal contraceptive, because in rodents it suppressed sperm production reversibly while maintaining muscle and bone mass. Research on S-23 focuses on bone and joint health.

Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated

Evidence: Preclinical — Animal and in-vitro studies only, no published human RCTs.
Evidence strengthPreclinical · 1/4
PreclinicalStrong human evidence

Animal and in-vitro studies only, no published human RCTs.

Chemical structure of S-23 (PubChem CID 24892822)
Structure via PubChem

Quick answer

S-23 is an investigational non-steroidal selective androgen receptor modulator originally studied as a candidate male hormonal contraceptive, because in rodents it suppressed sperm production reversibly while maintaining muscle and bone mass. It has never been approved for human use, has no published human clinical trials, and is prohibited at all times under the WADA code. Products sold online are unregulated research chemicals; analyses of the SARM market repeatedly find mislabelled or contaminated contents.

Class
Non-steroidal selective androgen receptor modulator (SARM)
Original purpose
Male hormonal contraceptive candidate
Evidence base
Rodent studies; no published human trials
Regulatory status
Not approved; not a lawful dietary supplement ingredient
Sport status
Prohibited at all times under the WADA code
Known effects in animals
Suppressed spermatogenesis and LH/FSH

Compiled by DoseRoutine from public sources including NIH/MedlinePlus, the FDA label, Mayo Clinic and PubChem. Educational information, not medical advice.

Plasma half-life
Not established
Default unit
mg

What published protocols report

Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.

Route studied
Oral in the rat pharmacology study that first characterized S-23[1]

Reported for S-23 in the cited sources. Published ranges are not dosing advice.

References & evidence

Documents the S-23 entry is written from. Each number matches an inline marker above.

  1. [1]Nonsteroidal selective androgen receptor modulators enhance female sexual motivationJones A, Hwang DJ, Duke CB 3rd, He Y, Siddam A, Miller DD, Dalton JT · Journal of Pharmacology and Experimental Therapeutics · 2010 · Peer-reviewed · PMID 20444881
  2. [2]Characterization of in vitro generated metabolites of the selective androgen receptor modulators S-22 and S-23 and in vivo comparison to post-administration canine urine specimensStarcevic B, Ahrens BD, Butch AW · Drug Testing and Analysis · 2010 · Peer-reviewed · PMID 20967890
  3. [3]Development of a multi-residue high-throughput UHPLC-MS/MS method for routine monitoring of SARM compounds in equine and bovine bloodXu W, Zhou X, Cai H, Xu W, Sun P, Sun L · Drug Testing and Analysis · 2020 · Peer-reviewed · PMID 32519780

How to track S-23 doses

S-23 is tracked as a protocol rather than a single reminder: a vial with a concentration, a schedule that may be titrated or cycled, and a rotation of injection sites. Here is the record that keeps all three consistent.

  1. 1

    Record the vial and concentration

    Log the vial strength and the volume of bacteriostatic water you added so S-23 is stored as a concentration rather than a guess. DoseRoutine converts that into mg per syringe unit and counts the doses left in the vial as you log.

  2. 2

    Set the schedule, not just a reminder

    Enter the dose in mg and the frequency. Cycled protocols get a start and end date so the history stays accurate when S-23 comes out of the routine.

  3. 3

    Rotate and log the injection site

    Pick the site at the moment you log the dose. The site map shows what you used last and how recently, which is the part that drifts fastest when two compounds run on different frequencies.

  4. 4

    Log adherence, not intentions

    Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.

  5. 5

    Review against outcomes

    Review S-23 alongside your logged metrics and any relevant blood work every few weeks before changing the dose, so the change is a response to data rather than to a good or bad day.

What to log each time

  • Dose in mg and the syringe units it worked out to
  • Vial: reconstitution date, concentration, doses remaining
  • Injection site and time
  • Any side effects in the 24 h after the dose
Reconstitution calculatorCompare dose tracking appsvs. Peptide TrackerTrack S-23 in DoseRoutine

References & Evidence

Sources on this page that document S-23 dosing, timing and safety.

  1. [1]National Center for Biotechnology Information View source

Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.

What is S-23 studied for?

Bone & Joint Health

What is S-23?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.

S-23 is an investigational selective androgen receptor modulator (SARM) that has been studied for its potential effects on muscle and bone tissue. SARMs are a class of therapeutic compounds that aim to have similar effects to androgenic drugs like anabolic steroids but with reduced androgenic side effects. S-23 is not approved for human use and remains a research chemical. Its primary mechanism involves binding to androgen receptors in a tissue-selective manner, potentially promoting anabolic activity in muscle and bone while minimizing effects on other tissues like the prostate or sebaceous glands. Early research on S-23 has been conducted primarily in animal models.

What does the research say about S-23?

Tap a section to expand.

S-23 functions as a selective androgen receptor modulator (SARM) through its high affinity and specificity for androgen receptors (ARs). Unlike traditional anabolic steroids, which activate ARs throughout the body, S-23 is designed to selectively activate ARs in muscle and bone tissue. This selectivity aims to induce anabolic (muscle-building) and osteogenic (bone-forming) effects while minimizing prostate enlargement, hair loss, and other androgenic side effects commonly associated with non-selective androgenic compounds. Upon binding to the androgen receptor, S-23 facilitates a conformational change that influences the recruitment of co-activator and co-repressor proteins, altering gene expression in target cells. The half-life of S-23 is approximately 12 hours, meaning it stays active in the body for an extended period, influencing receptor activity. This mechanism is still under investigation, and its full clinical implications and long-term effects in humans are not yet fully understood due to the limited human research available (PubChem).

Source for this section: Sources for How does S-23 work?: Jumps to this entry in the sources and references list at the end of the page.

Research on S-23 has primarily focused on its potential in animal models, showing effects on muscle mass and bone density. Studies have indicated that S-23 can increase lean muscle mass and bone mineral density in preclinical trials. These findings suggest a potential role for the compound in conditions associated with muscle wasting or bone loss. Further research has explored its capacity for increasing strength and endurance, though these observations are largely confined to non-human subjects. Some preclinical studies have also investigated its potential to improve fat oxidation and reduce body fat percentage. It is crucial to note that these potential benefits have not been definitively established in human clinical trials, and the compound is not approved for any therapeutic use (Examine.com).

Evidence for S-23 is predominantly derived from preclinical studies, particularly in rodent models. One animal study documented that S-23 demonstrated dose-dependent increases in muscle mass and bone mineral density while also showing a decrease in body fat (PubChem). Another study explored its potential as a male contraceptive agent, indicating that it could suppress spermatogenesis without causing significant adverse effects in animals, suggesting a complex interaction with the endocrine system. These studies highlight its potent binding affinity to androgen receptors. However, robust human clinical trials to establish efficacy, safety, and optimal dosing for any therapeutic indication are lacking. Therefore, all mentioned effects are based on preliminary animal research and are not confirmed in humans. The scientific community emphasizes the need for extensive human trials before any definitive conclusions can be drawn about its benefits or risks for human use (Examine.com).

Based on preclinical animal studies and anecdotal reports, potential side effects associated with S-23 may include suppression of natural testosterone production, which can lead to symptoms such as fatigue, decreased libido, and mood changes. Other reported, though unconfirmed, side effects in research settings or unverified human use, include aggression, hair loss, and potential adverse effects on liver and kidney function. Since S-23 is designed to be highly potent, its impact on the body, including potential off-target effects, requires careful consideration. The full spectrum of side effects in humans is unknown due to the lack of comprehensive clinical trials. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.

S-23 is an experimental compound and is not approved for human consumption by regulatory bodies like the FDA. Its use carries significant unknown risks due to the limited research, especially in humans. Individuals should be aware that purchasing or using S-23 outside of supervised research settings may carry legal and health risks. Due to its potent nature and potential for testosterone suppression, monitoring of hormonal levels and other physiological markers would be critical if ever considered for human use. The long-term effects on various organ systems are entirely unexplored. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.

Given that S-23 is a research chemical with no approved human use, there are no established contraindications. However, based on its proposed mechanism of action as a selective androgen receptor modulator, it would logically be contraindicated in individuals with a history of prostate issues, certain cancers (especially hormone-sensitive cancers), cardiovascular disease, or liver and kidney impairments. Pregnant or breastfeeding individuals should also avoid S-23 due to the unknown effects on fetal development or infant health. Its impact on the endocrine system implies that individuals with pre-existing hormonal imbalances or those undergoing hormone therapy would be at particular risk. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.

Due to the scarce data on S-23 in humans, specific interactions with other drugs, supplements, or compounds are largely unknown. However, because S-23 potentially affects androgen receptors and hormonal balance, caution is advised when co-administering with other substances that may also impact the endocrine system, liver, or kidneys. This includes, but is not limited to, other selective androgen receptor modulators (SARMs), anabolic steroids, hormonal therapies, liver-metabolized drugs, and potentially even certain supplements that influence hormone levels. Combining S-23 with any other potent compound could lead to unpredictable and potentially dangerous interactions, amplifying side effects or altering the efficacy of either substance. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.

S-23 has a reported half-life of approximately 12 hours. This suggests that if it were to be used, frequent daily administration might be considered to maintain stable levels in the body, typically once or twice daily. However, this compound is for research purposes only and not for human consumption. Establishing an optimal timing regimen would require extensive clinical trials to assess efficacy and minimize potential side effects, which are currently unavailable. As such, any discussion of timing is purely theoretical and does not constitute a recommendation for use. Dose is user-directed and must be set by a licensed clinician if ever approved.

Source for this section: Sources for When should you take S-23?: Jumps to this entry in the sources and references list at the end of the page.

What interacts with S-23?

Documented interactions for S-23: the other compound, the severity and confidence of the interaction, what happens, and what to do.
Interacts withSeverityTypeWhat happensWhat to do
Any peptide + hormoneNoteCategory ruleConfidence: theoreticalInjectable peptides plus hormones can have overlapping or compounding effects that aren't always well characterized.Source pendingTrack bloodwork with a provider; don't assume combinations are neutral.

Frequently asked questions about S-23

S-23 is a hormone. The references summarized come from NIH and PubMed records, FDA labeling where it exists, and Mayo Clinic patient material.

S-23 is commonly discussed in the context of supporting bone-joint. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.

For S-23, it is typically taken null. Always follow the specific dose your clinician or the product label prescribes.

S-23 carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Stop use and contact a clinician if you experience unexpected symptoms.

As a hormone, S-23 can overlap with other supplements, prescription medicines, hormones and peptides. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers S-23 with no sign-up.

Whether S-23 fits alongside testosterone replacement therapy depends on the protocol — dose, ester and ancillaries such as HCG or anastrozole — and on current bloodwork. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions

"Peptides" is not one category — healing peptides, GLP-1 agonists, growth-hormone secretagogues and melanocortins each behave differently next to S-23. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.

Published frequency for S-23 varies by protocol and formulation, so the label or prescription is what sets it. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps

The effect of a missed dose of S-23 depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.

For S-23 the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.

S-23 is not approved as a drug and the FDA has stated SARMs are not lawful dietary supplement ingredients, so products are sold under research-chemical labeling. Selling them for human consumption has drawn FDA warning letters, and possession rules vary by country. Anti-doping bodies treat any detected SARM as a violation. This is educational information, not medical advice.

In rats, S-23 bound the androgen receptor with high affinity, preserved muscle and prostate tissue and suppressed luteinising and follicle-stimulating hormone enough to halt sperm production, with fertility returning after withdrawal. That contraceptive suppression is the same mechanism that makes it hormonally disruptive when taken for physique purposes. This is educational information, not medical advice.

Because no human safety study exists, the risks are inferred from the SARM class: suppression of natural testosterone requiring recovery time, unfavourable HDL changes, and liver enzyme elevations, with case reports of drug-induced liver injury following SARM use. Unregulated sourcing adds the separate risk of getting a different or contaminated compound entirely. This is educational information, not medical advice.

Sources cited on this page

Specific documents referenced by the numbered markers above. Each number matches the marker in the text.

  1. PubChem CID 24892822(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/24892822

Verify at

Publisher search links for S-23. These are places to check the information — they are not citations, so they are not numbered.

DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.

What is the short answer on S-23?

Plain-text summary, safe to quote verbatim:

S-23 is an investigational non-steroidal selective androgen receptor modulator originally studied as a candidate male hormonal contraceptive, because in rodents it suppressed sperm production reversibly while maintaining muscle and bone mass. Research on S-23 focuses on bone and joint health.
Source: DoseRoutine — https://doseroutine.com/library/s-23

Cite this page

Using this in an article, AI answer, or research note? Please attribute:

DoseRoutine. (2026). S-23 — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/s-23
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