Andarine (S-4)

Structure: Non-steroidal SARM. Partial androgen receptor agonist with activity in muscle and bone. Shorter half-life than most SARMs requires split dosing.

Dosage:

• Bodybuilding: 25-50 mg/day for 6-8 weeks
• Split into 2-3 doses/day due to the short half-life (~4-6 hours)
• Lower doses (25-35 mg/day) to minimise visual side effects

Administration:

• Oral. Available as raw powder or liquid suspension (research-chemical grade only; no approved pharmaceutical form).
• Dosing 2-3 times daily due to short half-life. Avoid high single doses to reduce visual side effect risk.

Key Notes:

• Unique visual side effect: S-4 binds androgen receptors in the retina, causing a yellow or golden tint to vision (xanthopsia) and difficulty adjusting from bright light to darkness. This is dose-dependent, typically begins within 1-2 weeks, and resolves fully within 1-4 weeks of cessation.
• Visual side effects are not permanent at typical bodybuilding doses but can be disorienting and may affect night driving safety. Dose reduction or cessation resolves the issue.
• HPTA suppression is mild to moderate. Testosterone, LH, and FSH should be monitored. A SERM-based PCT is advisable after longer or higher-dose cycles.
• HDL suppression and mild liver enzyme elevation are consistent with other SARMs in its class.
• Less studied than ostarine or LGD-4033; published human clinical data is limited. Most available information is from animal studies and anecdotal human reports.
• Does not aromatise. Estradiol is not directly elevated.
• WADA prohibited under S1 (anabolic agents). Detection window is not well-characterised.
• Monitor: testosterone, LH, FSH, HDL, ALT, AST at baseline and post-cycle.