SARMs
S4 (Andarine)
S4 (Andarine) is a non-steroidal SARM researched for cutting and vascularity studies. Below, we compare vendors currently stocking research-grade S4 — not just a single sales page.
S4 (Andarine) is a non-steroidal SARM researched for cutting and vascularity studies. Below, we compare vendors currently stocking research-grade S4 — not just a single sales page.
Prices and testing claims are pulled from each vendor's product listing. Always confirm current price and COA (Certificate of Analysis) on the vendor's site before buying.
| Vendor | Price | Purity Testing | Code | |
|---|---|---|---|---|
 MuscleChemBest Value |
£49.99 | In-house testing | Buy Here → | |
 SwissChems |
$65.95 | Third-party COA | Buy Here → | |
 Next Chem |
$65.95 | Third-party COA | Auto-applied | Buy Here → |
 UK Sarms |
£54.97 | Third-party COA | Auto-applied | Buy Here → |
 Chemyo |
$79.99 (50mg/ml solution) | Third-party COA | Buy Here → |
S4 (Andarine) is a nonsteroidal selective androgen receptor modulator (SARM) developed by GTx Inc. in the same research program that produced Ostarine, studied for anabolic activity in muscle and bone tissue.
Research-grade S4 is typically supplied as capsules or a liquid solution, commonly at 25mg or 50mg per capsule, intended for laboratory research use only.
S4 binds the androgen receptor and is studied for tissue-selective anabolic activity similar to other SARMs; it additionally shows affinity for the androgen receptor in ocular tissue, a distinguishing pharmacological property compared to other compounds in the class.
Preclinical studies examined S4's effects on muscle and bone tissue as part of GTx's early SARM development program, alongside the related compound Ostarine, before development of S4 specifically was deprioritized.
S4's affinity for androgen receptors in ocular tissue is well documented in the research literature as the basis for reported visual side effects (such as difficulty adapting to darkness and yellow-tinted vision), a distinguishing safety consideration researchers cite when comparing S4 to other SARMs.
The visual disturbances associated with S4 are its most consistently documented and distinguishing reported effect, attributed to androgen receptor activity in eye tissue; it has not completed human efficacy trials at the level of Ostarine or LGD-4033, has no FDA approval, and is banned by the World Anti-Doping Agency.
No FDA-approved or large-scale human clinical trial dosage exists for S4. Doses referenced in available preclinical and limited early research are documented in that literature and do not constitute an established human protocol.
Compound X does not sell S4 (Andarine) directly. We provide independent research, comparisons and vendor links — see the vendor comparison table above for current US, UK, Canada and Australia options.
S4/Andarine research is indexed on PubMed under search terms such as "S4 Andarine SARM" and "GTx androgen receptor modulator ocular."
New guides, vendor comparisons and compound breakdowns every week.