What is Andarine?
Andarine, also S4 or S-4, is one of the older SARMs from the aryl-propionamide family. It was one of the first to be clinically evaluated. Clinical development was later not pursued.
Andarine is known mainly for a characteristic vision effect: a yellow tint to vision and worse night vision, occurring dose-dependently. This is not a myth but is reported consistently.
Comparison
SARMs compared
Five SARMs from the TPD lexicon, as described there. Tap a card to open its entry.
Simplified: all act on the androgen receptor and aim to address muscle and bone more than the prostate. There is no head-to-head comparison in humans. 32
How it works
Andarine binds the androgen receptor and activates it with tissue preference in muscle and bone. In animal models it was associated with maintaining bone density and reducing body fat.
The vision effect likely relates to how Andarine binds certain structures in the eye. It is reversible after stopping but bothersome during use.
Where it acts
Where andarine acted in experiments
Tap a point or a card. Colour = androgen receptor, grey = observed. All from rat studies.
- Skeletal muscle
Muscle mass and strength back to intact levels (castrated rats)3
AR - Bone
Bone density maintained, bones stronger (rats after ovary removal)1
AR - Fat tissue
Less body fat (rats after ovary removal)1
Observed in trials - Pituitary
LH and FSH fell in a dose-dependent way (castrated rats)3
AR - Prostate and seminal vesicles
Only 16 and 17 percent of the weight of intact animals (lower study dose)3
AR
Known targets7
Compound PubChem CID 9824562: one described target, Agonist in muscle, bone and pituitary, weak in the prostate.
- Gene
- AR
- UniProt
- P10275
- ChEMBL
- CHEMBL1871
- Action
- Agonist in muscle, bone and pituitary, weak in the prostate
How to take it
Oral, often split because of the short half-life.
- Half-life only around 4 hours, so often morning and evening.
- With some water, with or without food.
- Cycles are usually kept short.
Dosing
Dosing
Dosing, titration and syringe
Loading the dosing information …
- Getting started and stepping up, drawn as a staircase
- Units on the U-100 syringe for every step
- How long one vial lasts
What the research shows
A preclinical study (Kearbey, 2007) showed in ovariectomized rats that S-4 maintained bone density and bone strength while reducing body fat. That is a solid animal result.
Solid modern human data on muscle building in healthy people are scarce, clinical development was discontinued. The Solomon review (2019) places Andarine in the SARM context.
Study results
What the trials measured
Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.
Androgenic organs after eight weeks3
Organ weight in percent of intact animals (intact = 100%)
Values from the abstract. In the same experiment andarine brought the soleus and levator ani muscle to the level of intact animals. The comparison androgen DHT made the prostate and seminal vesicles grow to more than double. Rat model, not tested in humans.
Research status
Where the research stands
Where the compound stands on the way from lab research to approval. As of 26 Oct 2026. 6
- Preclinical Rat studies on muscle, bone, fat and pharmacokinetics (2004 to 2007)
- Phase 1 no registered trial
- Phase 2 no registered trial
- Phase 3 no registered trial
- Approval not yet
So far there is no registered trial in humans. 6
Side effects
- Characteristic vision effect: yellow tint, worse night vision, dose-dependent and reversible after stopping.
- Dose-dependent suppression of the testosterone axis.
- Falling HDL values.
Practice
-
Stay low, the vision effect scales directly with the dose.
-
Short cycles, then a break.
-
Banned in official competition and detectable (WADA S1.2).
Storage
Store dry, cool and protected from light, out of reach of children. Keep the original container closed and mind the expiry date.
