S‑23

S‑23 exhibits high selectivity for androgen receptors in muscle tissue, leading to increased protein synthesis and reduced muscle breakdown. Unlike non-selective SARMs or testosterone, it demonstrates minimal impact on tissues like the prostate. This targeted action may contribute to its anabolic effects with fewer androgenic side effects—though this is still under research. S‑23 binds directly to the AR receptor, initiating a cascade of intracellular events that promote muscle growth and strength gains. It’s important to note users report varying degrees of receptor affinity based on individual genetic factors.

Athletes typically run S‑23 during cutting cycles, aiming to preserve lean muscle mass while in a caloric deficit. Researchers also investigate its potential for recomping – simultaneously building muscle and reducing body fat—though results vary significantly. Some users report employing it post-cycle as a bridge to minimise muscle loss between longer steroid cycles. While not traditionally used for bulking, some athletes use lower dosages alongside other compounds. S‑23 is not typically used in PCT protocols due to its potent nature.

Advanced users typically run S‑23 at doses of 250–400 mg/week, divided into multiple injections (e.g., twice weekly). Intermediate users may start with 100–200mg/week and assess tolerance before increasing. Cycle lengths generally range from 8 to 12 weeks. It's crucial to monitor bloodwork throughout the cycle; specifically, estradiol levels should be assessed. Users report that exceeding 400 mg/week does not proportionally increase results but significantly elevates risk of side effects.

Users report potential side effects including suppression of natural testosterone production, mild liver stress (hepatotoxicity), and temporary reductions in sperm count. Age 21+ is strongly advised due to the impact on hormonal systems. A robust PCT protocol is essential post-cycle, incorporating SERMs like Clomiphene or Nolvadex to restore endogenous testosterone levels. Regular bloodwork (liver enzymes, testosterone, estradiol) is critical throughout and after the cycle. Some users report increased aggression; monitoring psychological state is advised.

Mechanism of action

S‑23 selectively binds to androgen receptors in muscle and bone tissue, promoting protein synthesis, increasing muscle mass, and reducing fat accumulation through activation of intracellular signalling pathways.