Overview
Andarine is a selective androgen receptor modulator (SARM) — a class of compounds that selectively bind to androgen receptors in muscle and bone tissue. First-generation selective androgen receptor modulator.
With a half-life of ~4 hours, Andarine requires daily administration in most observed protocols. Taken orally, it has a bioavailability of approximately 95% via its primary route.
Half-life approximately 4 hours. Short half-life necessitates split dosing for stable plasma levels. High oral bioavailability. One-compartment model. Not FDA-approved for human use.
Mechanism of Action
Andarine's pharmacological activity involves the following key pathways:
Selective Receptor Binding
Andarine is designed to selectively bind to androgen receptors in muscle and bone tissue, with reduced activity in other androgen-sensitive tissues.
Tissue Selectivity
The selectivity of Andarine is achieved through differential coactivator recruitment — the compound activates different downstream pathways depending on the tissue type.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
25 mg/day
Route
Oral
Frequency
2-3 times daily
Duration
8-12 weeks
Dose
50 mg/day
Route
Oral
Frequency
2-3 times daily
Duration
8-12 weeks
Frequently Asked Questions
What is Andarine (S-4) and how does it work?
Andarine (S-4) is an orally active, non-steroidal selective androgen receptor modulator (SARM) that functions as a partial agonist of the androgen receptor. It was originally developed for conditions such as muscle wasting and osteoporosis. In preclinical studies, Andarine demonstrated the ability to restore levator ani muscle weight while producing significantly less effect on prostate weight, illustrating its tissue-selective profile.
What is the half-life of Andarine (S-4)?
Andarine has a commonly cited half-life of approximately 4–6 hours based on preclinical data, though published human pharmacokinetic data remains limited. This shorter half-life compared to other SARMs means split dosing (2–3 times per day) is frequently observed in community protocols to maintain more stable plasma concentrations throughout the day.
Does Andarine cause vision side effects?
A yellow tint to vision (xanthopsia) and difficulty adjusting between light and dark environments are the most distinctive reported effects of Andarine. These visual changes are believed to result from the compound's affinity for retinal receptors and are highly dose-dependent, occurring more frequently at doses above 50 mg/day. They are consistently reported as reversible, typically resolving within 2–3 days of discontinuation or dose reduction.
How long does Andarine take to show results?
Due to its short half-life, Andarine reaches steady-state concentrations rapidly – typically within 1–2 days of consistent dosing. Increased vascularity and a harder, drier appearance are commonly reported within the first 1–2 weeks. Andarine is most frequently used for cutting and recomposition goals, with full effects on body composition generally observed over 6–8 weeks.
What is the typical Andarine (S-4) cycle length?
Cycle lengths of 6–8 weeks are most commonly observed, with 8 weeks being a frequently reported maximum. Shorter cycles are sometimes preferred to minimize the likelihood of vision-related effects. A 5-days-on, 2-days-off dosing pattern is sometimes reported as a strategy to manage vision side effects while maintaining efficacy.
Can Andarine be used for cutting and recomposition?
Andarine is most commonly associated with cutting and body recomposition goals rather than pure bulking. Users frequently report a harder, more vascular appearance, and improved muscle definition during caloric deficits. It is often described as one of the milder SARMs in terms of overall mass gain but effective for maintaining lean tissue and improving visual composition during fat loss phases.