Andarine (S4) — Dosing, Cycles, Half-Life & Side Effects

Andarine (S4) is a selective androgen receptor modulator (SARM) with a half-life of 4-6 hours. Aryl-propionamide SARM (GTx-007): partial androgen-receptor agonist on prostate, fuller agonist on muscle/bone in rodents. No published human Phase II/III trial; rat plasma half-life 2.6-5.3h (Kearbey 2004). Vision side effects (yellow tint, nyctalopia) widely user-reported but no peer-reviewed mechanistic paper. This page is educational harm-reduction reference compiled from peer-reviewed literature — not medical advice, not an endorsement, not a recommendation to use. Consult a licensed clinician before any decision.

Quick Facts

ClassSelective Androgen Receptor Modulators
Half-life4-6 hours
Detection window7 days
AromatizationNo
HepatotoxicityLow
Suppression4/10
17α-alkylatedNo
Administrationoral

Typical Dosing Ranges

Common dose range: 25-75mg/day

Cycle length: 8-12 weeks

Time to steady state: ~1 days

Dose ranges are compiled from published pharmacokinetic studies and community-reported usage. Where a value is community-reported rather than clinically studied, this page and its structured data flag it. Lower end of any range is always the safer starting point.

Stacking Considerations

  • No structural stacking blockers. Standard harm-reduction rules apply: minimize total androgen load, minimize oral exposure, and monitor bloodwork.

PCT Requirements

  • Depot clearance estimate: ~1 days post-last-dose before SERM start (5 × apparent depot half-life of 4h).
  • Never stack two SERMs. Extend a single SERM (tamoxifen OR enclomiphene/clomiphene) rather than combining.
  • Use the cycle planner to generate a full protocol based on your complete stack, not this compound alone.

Side Effect Profile

  • Vision changes
  • Short half-life
  • Limited research

Known Interactions

No compound-specific interactions are catalogued in the current matrix. This does not mean no risk exists — it means there is no curated pairwise entry.

Related compounds

Monitoring (Bloodwork & Vitals)

  • Comprehensive metabolic panel (baseline, mid-cycle, post-cycle)
  • Lipid panel (total cholesterol, HDL, LDL, triglycerides)
  • CBC (hemoglobin, hematocrit — watch for erythrocytosis)
  • Sex-hormone panel (Total T, Free T, Estradiol sensitive, SHBG, LH, FSH)
  • Blood pressure (weekly self-check; flag systolic >140 or diastolic >90)

Baseline bloodwork is recommended before any cycle. Discontinue if liver enzymes exceed 3× upper limit of normal or if hematocrit exceeds 54%.

Frequently Asked Questions

What is the half-life of Andarine (S4)?

Andarine (S4) has a half-life of approximately 4-6 hours. Clearance estimate: 4h × 5 = 20h = 1 day. This figure is used to determine injection frequency (for esters) and post-cycle clearance timing.

What is the typical dose range for Andarine (S4)?

Commonly reported ranges for Andarine (S4): 25-75mg/day. Cycle length: 8-12 weeks. These are compiled from published studies and community-reported usage — individual response varies and lower end is always preferred.

Does Andarine (S4) suppress natural testosterone?

Andarine (S4) causes moderate suppression of the HPTA axis (score 4/10). PCT may still be advisable depending on stack and duration.

Is Andarine (S4) liver toxic?

Hepatotoxicity rating: Low. Non-17αα compound — liver stress is lower but still warrants periodic monitoring during a cycle.

Does Andarine (S4) aromatize to estrogen?

Aromatization profile: No. Minimal to no aromatization expected, so aromatase inhibitors are not typically indicated for this compound alone.

What is Andarine (S4) typically used for?

Andarine (S4) is commonly used for: Cutting, Fat loss, Beginner cycles. Intended-use context does not imply safety — every use case carries the same underlying pharmacological risks.

Citations

  1. Kearbey JD et al.. 2004. Xenobiotica — Half-life 3-4 hours in rat; no human PK data available
  2. Gao W et al.. 2005. Endocrinology — HPTA effects in animal models; moderate suppression observed
  3. Perera MA et al.. 2006. Drug Metab Dispos — Andarine pharmacokinetics in dog model
  4. Kearbey JD et al.. 2007. Pharm Res — S-4 preserves bone mineral density and reduces body fat in ovariectomized rats — bone-protective preclinical evidence
  5. Simitsidellis I et al.. 2019. J Endocrinol — GTx-007 (Andarine) had minimal uterotrophic effect vs DHT/GTx-024, supporting partial-agonist profile
  6. Van Wagoner RM et al.. 2017. JAMA — Only 52% of products labeled as SARMs contained the labeled compound; 39% contained other unapproved drugs — quality-control caveat applies broadly to SARM supplements
  7. Gao W, et al. Selective androgen receptor modulator treatment improves muscle mass and strength, and reduces bone turnover in older men. J Clin Endocrinol Metab 2005

Disclaimer

StackItSmart is an independent harm-reduction reference. The content above is compiled from peer-reviewed literature and is not medical advice, not an endorsement, and not a recommendation to use Andarine (S4). Performance-enhancing compounds carry legal, endocrine, cardiovascular, and hepatic risks. Consult a licensed clinician before any decision. StackItSmart does not provide sourcing, procurement, or dosing prescriptions.

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