Andarine (S4)

What it is

Andarine was one of the first selective androgen receptor modulators developed, investigated for muscle wasting and benign prostatic hyperplasia. Development was discontinued and it was never approved. It is now sold online as a research chemical.

What’s claimed

• Lean mass gain with simultaneous fat loss
• Improved strength without water retention
• A milder alternative to newer SARMs

What the evidence shows

The muscle and bone effects were demonstrated in animal models; there is no meaningful controlled human efficacy evidence (Bronze, animal basis). What andarine is genuinely known for in humans is its characteristic visual side effect: a yellow tint to vision and difficulty adapting to darkness, caused by its interaction with receptors in the retina. It is reported as reversible, but the fact that a compound with no approval readily produces a visual effect is a warning about how little is known about the rest of its activity.

The risks

• Ocular: a yellow tint to vision and impaired night vision, characteristic of this compound.
• Endocrine: suppression of natural testosterone production.
• Lipids: marked lowering of HDL ('good') cholesterol and raising of LDL, an adverse cardiovascular shift that is more pronounced with oral compounds.
• Product risk: manufactured outside any regulatory system. Independent testing repeatedly finds these products mislabelled, under- or over-concentrated, or containing entirely different active drugs, so the real exposure is unknowable from the label.

What needs monitoring

• Liver function tests
• Lipid profile
• Testosterone and the hormonal axis
• Any visual change is a reason to stop and see a doctor, not something to work around.