Andarine (S-4)
Andarine (S-4) is an early non-steroidal SARM studied mainly in animals for muscle and bone. Human evidence is essentially absent, so claims rest on preclinical work and anecdote. It is notable for a distinctive, reversible visual side effect (yellow tinting and night-vision problems) at higher doses, alongside the usual testosterone suppression.
01 Overview
S-4 was one of the first SARMs developed by GTx and is well characterised in rodent models for preserving muscle and bone mass, but it never advanced far in human development. Its short half-life led to frequent daily dosing in anecdotal protocols.
The compound is best known recreationally for a dose-dependent visual disturbance: users report a yellow tint to vision and difficulty adjusting to darkness, thought to arise from binding at retinal receptors. The effect is reported as reversible on cessation. As with all SARMs, andarine is unapproved, prohibited in sport, and sold only as a research chemical.
02 Mechanism
Non-steroidal androgen-receptor partial agonist selective for muscle and bone; a metabolite is thought to interact with retinal receptors, producing visual effects.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Light | 25–50 mg/day | Oral | Anecdotal range, usually split due to short half-life. |
| Common | 50–75 mg/day | Oral | Higher doses increase risk of visual disturbances. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Preservation of muscle and boneRodent studies show maintenance of muscle mass and bone density after castration. | Preclinical | ||
| Muscle hardness and recompositionUsers report improved muscle definition; unsupported by human trials. | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| HDL cholesterol reductionReported reductions in HDL, as with other SARMs. | Mild | Common | Anecdotal | |
| Visual disturbances (yellow tint, night-vision loss)Dose-dependent yellow tinting of vision and difficulty adapting to darkness, reported as reversible after stopping. | Moderate | Common at higher doses | Anecdotal | |
| Testosterone suppressionSuppression of endogenous testosterone reported, consistent with androgen-receptor agonism. | Moderate | Common | Anecdotal |
06 Commonly used with
What andarine is combined with, and why. This is about intent rather than safety — the interactions table below covers what is dangerous. Nothing here is listed without what it costs.
| Compound | Frequency | Purpose & trade-off |
|---|---|---|
| Stacked compounds | ||
| Ostarinecutting | Andarine is stacked with ostarine in a cut for its hardening effect while ostarine helps hold onto lean mass.Trade-off: Both are suppressive, and andarine specifically is known for a dose-dependent yellow-tinted vision side effect. | |
| Cardarineshredding triple | Part of the popular andarine/ostarine/cardarine 'shredding' triple, cardarine adds endurance and fat loss to the hardening effect.Trade-off: Cardarine's rodent tumour signal and no human data mean the triple layers an unproven risk onto two already-understudied SARMs. | |
| StenabolicSR9009 | Stenabolic is added as a non-hormonal metabolic and endurance agent to intensify the fat-loss aim of a cutting stack.Trade-off: Stenabolic has poor oral bioavailability and a very short half-life, so real-world effects are questionable and human data is absent. | |
| Post-cycle | ||
| TamoxifenPCT | A SERM PCT is used after andarine because it is suppressive, especially at the higher doses needed for its hardening effect.Trade-off: A SERM cannot reverse the vision changes and does not make a compound with thin human safety data safe. | |