Andarine

I’ll be honest with you — Andarine is one of those compounds I approach with serious caution. Not because it doesn’t work. The animal research is actually pretty compelling. But because it was literally abandoned by the pharmaceutical company that created it, and the reason why should give anyone pause.

If you’ve landed here, you’re probably deep in the SARM rabbit hole, weighing your options for a cutting cycle or recomp. You’ve seen the forum posts about “dry, hard gains” and “Winstrol-like effects without the liver damage.” And yeah, some of that tracks. But there’s a lot more to the story — including a side effect so unusual it’s become Andarine’s defining characteristic.

The Short Version: Andarine (S-4) is a SARM with solid preclinical evidence for muscle preservation and bone health, but zero published human trials. Its development was discontinued due to dose-dependent vision disturbances. It’s most popular as a cutting compound, but you’re essentially self-experimenting with an abandoned drug candidate. Below, I break down the science, the real risks, and whether it’s worth considering.

What Is Andarine?

Andarine — also called S-4 or GTx-007 — is a synthetic selective androgen receptor modulator developed in the early 2000s by researchers at GTX, Inc. and the University of Tennessee. It was designed to treat muscle wasting diseases like cachexia, osteoporosis, and benign prostatic hyperplasia, conditions where you need anabolic activity in muscle and bone without hammering the prostate or triggering estrogenic side effects.

Three Phase 1 clinical trials involving 86 healthy volunteers were completed back in 2003. That’s about as far as it got. GTX pulled the plug on S-4 after observing vision disturbances during testing and pivoted to developing Ostarine — a structurally improved successor compound that didn’t mess with your eyesight.

Today, Andarine sits in a regulatory gray zone. It’s not FDA-approved for any human use. It’s been on the WADA Prohibited List since 2008. And it’s sold online as a “research chemical” — which, let’s be real, is a legal fig leaf. The vast majority of people buying it aren’t running lab experiments on rodents.

Here’s the thing I always come back to: if a pharmaceutical company with millions in R&D funding decided this compound wasn’t worth pursuing, that tells you something. It doesn’t mean Andarine is useless. It means the risk-benefit math didn’t work out for clinical development. Whether that math works for your personal situation is a different calculation — one I want to help you make with full information.

How Does Andarine Work?

Think of androgen receptors like locks scattered throughout your body — in your muscles, bones, prostate, skin, brain, and yes, your eyes. Traditional anabolic steroids are like a master key that opens every single one of those locks indiscriminately. That’s why they build muscle but also cause acne, prostate growth, hair loss, and a laundry list of other problems.

Andarine was designed to be a selective key. It binds to androgen receptors with high affinity — about 4 nanomolar, which is strong — but it preferentially activates receptors in muscle and bone tissue while largely ignoring the prostate and skin. The technical term is “tissue selectivity,” and it’s the entire premise behind SARMs as a drug class.

A landmark 2005 study by Gao et al. in Endocrinology demonstrated this selectivity beautifully. In castrated rats, S-4 at 3 mg/kg restored soleus muscle mass and strength to levels matching intact animals — while only bringing prostate weight back to 16% of normal. That’s a massive therapeutic window between the effects you want and the ones you don’t.

The compound also isn’t a substrate for 5α-reductase or aromatase. In practical terms, that means it doesn’t convert to DHT (which would amplify androgenic effects in the prostate and scalp) and it doesn’t convert to estrogen (so no gynecomastia or water retention). These are genuine advantages over traditional androgens.

But here’s the catch nobody figured out until it was too late: Andarine also binds to androgen receptors in your retina. Your eyes have androgen receptors — who knew? — and S-4 activates them, which is why users report that signature yellow-tinted vision. The compound’s designers didn’t anticipate this off-target effect, and it’s ultimately what killed the program.

Reality Check: Despite the promising mechanism, Andarine has zero published human efficacy data. Every benefit claim you’ll see is extrapolated from rat studies or anecdotal bodybuilding reports. That doesn’t make the mechanism wrong — it means we’re guessing about how it translates to humans.

Benefits of Andarine

Let me be upfront about the evidence quality here. What we have is almost entirely animal data. It’s well-conducted animal data, but the gap between “works in castrated rats” and “works in healthy humans” is enormous. Here’s what the research actually shows:

Muscle Preservation and Strength

Gao et al. (2005) demonstrated that S-4 at 3 and 10 mg/kg restored soleus muscle mass, strength, and levator ani muscle mass to intact levels in castrated rats. It also reversed castration-induced loss in lean body mass. For a compound designed to treat muscle wasting, these are exactly the results you’d want to see in preclinical work.

Bone Health

Kearbey et al. (2006) in Pharmaceutical Research showed that S-4 maintained whole body and trabecular bone mineral density, cortical content, and actually increased bone strength in ovariectomized rats over 120 days. In the Gao study, S-4 produced a larger increase in total body BMD than DHT itself. For osteoporosis applications, that’s a significant finding.

Fat Loss

The Kearbey study also noted reduced body fat in the S-4 treatment groups. This aligns with what the bodybuilding community reports — that Andarine promotes a “drier,” leaner physique during cutting phases.

What Users Actually Report

Anecdotally, people running 8-week S-4 cycles describe gaining roughly 5 pounds of lean mass, losing 4-5% body fat, and noticing a “hardening” effect on muscles — increased vascularity, better definition, and a drier aesthetic. Strength gains are modest but real, with some users breaking personal records around week 5.

Important: These user reports are not controlled evidence. People running S-4 are also typically training hard, eating in a caloric deficit, and may be stacking other compounds. Isolating S-4’s contribution is impossible from anecdotal data alone.

How to Take Andarine

Disclaimer first: No clinically established human dosage exists. What follows comes entirely from community-reported protocols. You are your own lab rat here.

Dosage ranges commonly reported:

• Starting dose: 25 mg/day — this is where most people begin to assess tolerance, especially regarding vision effects
• Standard dose: 50 mg/day — the most commonly used dose in the bodybuilding community
• Upper range: 75 mg/day — significantly increases vision side effect risk with diminishing returns

Timing matters. Andarine has a short half-life of roughly 4 hours based on preclinical pharmacokinetic data. That means a single daily dose creates a spike-and-crash pattern. Most users split their dose into 2-3 administrations throughout the day — for example, 25 mg in the morning and 25 mg in the afternoon for a 50 mg total daily dose. Oral bioavailability is dose-dependent, ranging from 38% to 91% in animal studies, with lower doses absorbing more efficiently.

Cycling protocol:

• Typical cycle length: 6-8 weeks
• Many users follow a 5 days on / 2 days off schedule, specifically to give the retinal androgen receptors a break and manage vision side effects
• Post-cycle therapy is recommended due to testosterone suppression — usually beginning immediately after the last dose

Pro Tip: Start at 25 mg/day for the first week regardless of your experience with other SARMs. Andarine’s vision side effects are highly individual — some people notice nothing at 50 mg while others get significant visual disturbance within 10 days at the same dose. Give yourself time to see how your eyes respond before escalating.

Available forms:

• Liquid solution (most common — typically 25-50 mg/mL in PEG-400)
• Capsules
• Raw powder

Liquid solutions are the most popular because they allow precise dose titration. If you’re getting capsules, you’re locked into whatever dose the manufacturer chose.

Side Effects and Safety

This is the section you actually need to read carefully. Andarine’s side effect profile has some unique features that set it apart from every other SARM.

The Vision Thing

This is Andarine’s calling card — and not in a good way. Users report yellow-tinted vision (the medical term is xanthopsia), reduced night vision, and difficulty adjusting between bright and dark environments. It typically onset around weeks 2-3, gets worse at higher doses, and is strongly dose-dependent above 50 mg/day.

The good news: it’s reversible. Vision typically returns to normal within days of stopping the compound, sometimes within 24-48 hours. The mechanism is straightforward — S-4 binds androgen receptors in retinal tissue, and when you stop taking it, those receptors clear and vision normalizes.

The less good news: no one has studied what happens to retinal tissue with repeated or prolonged exposure to an androgen receptor agonist. “Reversible in the short term” and “safe for your eyes long-term” are not the same statement.

Hormonal Suppression

Andarine suppresses LH and FSH production in a dose-dependent manner. Your natural testosterone output will decrease during a cycle. Anecdotally, suppression is reportedly less severe than LGD-4033 or RAD-140, but more significant than Ostarine. Post-cycle therapy is not optional.

Liver Concerns

Here’s something most SARM forums gloss over. Andarine contains an aromatic nitro substituent and a substructure similar to paracetamol’s toxicophore — meaning it can form reactive, hepatotoxic derivatives during liver metabolism. SARMs as a class have been associated with drug-induced liver injury in case reports. If you have any pre-existing liver issues, this compound is not for you.

Other Reported Effects

• Lipid disruption (shifts in HDL/LDL cholesterol)
• Mild headaches
• Nausea at higher doses
• Hair shedding (rare, and less common than with traditional steroids)

Important: Andarine is absolutely contraindicated during pregnancy and breastfeeding — androgenic compounds can cause birth defects. It should also be avoided by adolescents, anyone with pre-existing liver or retinal conditions, and competitive athletes (it’s a banned substance with detectable metabolites).

Stacking Andarine

If you’re going to run Andarine, here’s how the community typically combines it — along with some important cautions.

The Classic Cutting Stack: Andarine (50 mg/day) + Cardarine (20 mg/day) for 8 weeks. Cardarine adds endurance and fat oxidation without any additional hormonal suppression since it’s a PPARδ agonist, not a SARM. This is probably the most popular S-4 stack for a reason — it addresses cutting from two different angles without compounding side effects.

The Triple Stack: Andarine (50 mg/day) + Ostarine (25 mg/day) + Cardarine (20 mg/day) for 8-12 weeks. Widely cited as the go-to cutting combination in the SARM community. More suppressive than S-4 alone, so PCT becomes even more important.

Recomposition: Andarine + Ostarine is frequently used for simultaneous lean muscle gain and fat reduction.

Supportive supplements to run alongside any S-4 cycle:

• Liver support: NAC, TUDCA, Milk Thistle
• Lipid support: Fish Oil
• General health: a quality multivitamin with Vitamin D and Zinc

What NOT to stack with Andarine:

• Other hepatotoxic compounds, including oral anabolic steroids and excessive alcohol
• Aromatase inhibitors — S-4 doesn’t aromatize, so AIs are unnecessary and can crash your estrogen into the ground
• Other vision-affecting substances or medications

My Take

I’ll cut straight to it: Andarine is a compound I respect scientifically but have a hard time recommending enthusiastically.

The preclinical data is genuinely promising. The tissue selectivity is impressive. And the anecdotal reports from experienced users are consistent enough that I believe S-4 does what people say it does — modest muscle hardening, enhanced fat loss during a cut, and that dry aesthetic look. It’s not placebo.

But here’s what I keep coming back to. The company that invented this compound — the people who understood its pharmacology better than anyone on earth — decided it wasn’t worth developing further. They had the Phase 1 data. They had the preclinical data. And they still walked away. That’s a data point you can’t ignore.

The vision side effects are the obvious concern, but what bothers me more is what we don’t know. There are no long-term safety studies. There’s no published human efficacy data. And the SARM market is notoriously contaminated — a 2009 study by Thevis et al. found Andarine being sold disguised as “green tea extract” with roughly 10% impurities. You don’t always know what you’re actually getting.

If you’re considering S-4 for cutting, Ostarine achieves similar goals with a better safety profile, more human data, and no vision side effects. It’s literally the compound that was designed to replace Andarine. For most people, that’s the smarter choice.

If you’ve already decided to run Andarine despite all of this — start low (25 mg/day), use the 5-on/2-off protocol, keep your cycle to 8 weeks max, run liver support, get bloodwork before and after, and have your PCT ready before you take the first dose. And if you notice any vision changes, drop the dose immediately or discontinue entirely. Your eyesight is not worth a slightly better physique.

This is one of those cases where the foundations matter more than ever. Dial in your training, nutrition, sleep, and stress management first. Those interventions are free, proven, and won’t mess with your retinas. If you’ve already optimized all of that and still want an edge, at least you’ll be making the decision from a place of knowledge rather than desperation.