In case you’ve been researching SARMs for slicing, recomposition, or lean muscle retention, chances are high you’ve stumbled throughout S4, also referred to as Andarine. Touted as one of many “dryest” SARMs available on the market, S4 is in style amongst physique athletes for its skill to extend fats loss, vascularity, and muscle density—with out the water retention and bloating of conventional anabolic steroids.
However beneath the floor lies a compound that’s misunderstood, under-researched, and infrequently misused. Whereas it could look like a really perfect shortcut to getting shredded, Andarine comes with its personal dangers—particularly in relation to imaginative and prescient uncomfortable side effects, suppression, and questionable sourcing.
On this information, we’ll cowl:
→ What S4 is and the way it works within the physique
→ The advantages you’ll be able to realistically count on from a correctly dosed cycle
→ Potential uncomfortable side effects—particularly the infamous “yellow imaginative and prescient”
→ Dosage, cycle size, stacking protocols, and post-cycle remedy
→ Authorized standing, sourcing considerations, and smarter options
Whether or not you are simply studying about SARMs otherwise you’re already contemplating an S4 cycle, that is the no-nonsense breakdown you want earlier than making any selections.
What Is S4 (Andarine)?
S4, also referred to as Andarine, is a Selective Androgen Receptor Modulator (SARM) developed by GTx, Inc. for treating muscle losing, osteoporosis, and benign prostatic hyperplasia (BPH). Like different SARMs, S4 is designed to bind selectively to androgen receptors in muscle and bone tissue, stimulating anabolic exercise with out triggering the full-body androgenic results related to anabolic steroids.
→ S4 binds with excessive affinity to androgen receptors in skeletal muscle, selling lean muscle preservation throughout caloric restriction
→ It was initially researched as a therapeutic agent to shrink the prostate with out affecting muscle mass—an impact not potential with conventional DHT blockers
→ In comparison with stronger SARMs like RAD-140, S4 is taken into account extra gentle, although nonetheless suppressive
→ Its distinctive chemical construction offers it a quick half-life (~4 hours), requiring cut up dosing all through the day for regular plasma ranges
“Andarine was developed as a non-steroidal SARM able to retaining anabolic exercise in muscle whereas selectively decreasing prostate measurement, exhibiting promise for each athletic and scientific purposes” (Dalton et al., Present Opinion in Scientific Diet & Metabolic Care).
As a result of it doesn’t aromatize into estrogen, S4 doesn’t trigger water retention or gynecomastia, making it a most well-liked possibility for slicing or recomposition cycles. Nonetheless, its affect on imaginative and prescient receptors units it aside from different SARMs—one thing we’ll discover intimately later.
For an entire breakdown of how SARMs work, take a look at our information on What Are SARMs?
How S4 (Andarine) Works
S4 works by selectively binding to androgen receptors in muscle and bone tissue. As soon as certain, it prompts anabolic pathways that promote muscle protein synthesis, nitrogen retention, and bone energy—with out stimulating androgen receptors within the prostate, pores and skin, or different tissues vulnerable to undesirable uncomfortable side effects.
→ S4 is a partial agonist of the androgen receptor, that means it stimulates muscle-building exercise with out absolutely activating androgenic results in non-target tissues
→ It mimics the results of testosterone in muscle and bone, however avoids most of the undesirable outcomes like prostate enlargement, oily pores and skin, or aggression
→ In comparison with different SARMs, S4 has a quick half-life (3–6 hours), which requires cut up dosing (usually twice every day) to take care of secure blood concentrations
→ S4 has a robust anabolic-to-androgenic ratio, contributing to its lean, dry look with minimal bloat or water retention
“Andarine exerts its results by way of high-affinity binding to androgen receptors in skeletal muscle, selling anabolic exercise with minimal androgenic stimulation in reproductive tissues” (Yin et al., Journal of Medicinal Chemistry).
Its partial agonist profile is a double-edged sword. Whereas it could lead to fewer androgenic uncomfortable side effects, it could actually additionally imply weaker anabolic results than full agonists like RAD-140 or LGD-4033. That’s why many customers choose to make use of S4 in a slicing or recomposition cycle, the place preservation and definition matter greater than uncooked mass.
Now that mechanism of motion is roofed, the Advantages part you already accepted flows completely subsequent. Would you wish to proceed with the Facet Results part now?
Advantages of S4 (Andarine)
S4 (Andarine) is greatest identified for its skill to improve muscle hardness, vascularity, and fats loss—all with out water retention. This makes it a go-to alternative for physique athletes in slicing or recomp phases. Whereas not as highly effective for mass-building as LGD-4033 or RAD-140, its lean, dry aesthetic makes it very best for physique composition refinement.
→ Fats Loss and Muscle Retention Throughout a Lower
S4 has been proven to protect lean muscle mass in a calorie deficit whereas concurrently enhancing lipolysis. It doesn’t immediately burn fats—however it helps physique recomposition by preserving muscle whereas fats is misplaced, resulting in improved general definition.
“Selective androgen receptor modulators like Andarine have demonstrated the flexibility to take care of lean mass throughout catabolic situations with out growing androgenic uncomfortable side effects” (Kearbey et al., Endocrinology).
→ Elevated Muscle Density and Vascularity
In contrast to bulking compounds that add mass and water weight, S4 creates a dense, dry, and outlined look. Customers usually report improved muscle separation, hardness, and elevated vascularity inside 2–3 weeks of use.
→ No Estrogen Conversion
As a result of S4 does not aromatize into estrogen, it avoids points like water retention, gynecomastia, or puffiness—issues generally related to steroids like Dianabol or Anadrol. This makes it a powerful alternative for physique athletes chasing a dry, sharp, contest-ready look.
→ Muscle Preservation for Chopping and Recomp
S4 shines when energy are low. It permits customers to maintain onto hard-earned muscle whereas leaning out, making it particularly worthwhile for people working lengthy cuts, pre-contest protocols, or summer season shreds.
For these in search of a dry, sharp physique with out estrogen-related uncomfortable side effects, S4 affords a compelling—although not facet impact–free—possibility.
Facet Results of S4 (Andarine) — Particularly the Imaginative and prescient Downside
S4 has a definite side-effect profile in comparison with different SARMs, most notably its dose-dependent imaginative and prescient disturbances. Like all SARMs, it could actually additionally suppress pure testosterone, disrupt blood lipids, and affect liver enzymes. Deal with it like a hormone-modulating drug—not a innocent shortcut.
→ Imaginative and prescient Modifications (Night time Blindness, Yellow Tint, Mild/Darkish Adaptation Points)
Customers ceaselessly report xanthopsia (yellow-tinted imaginative and prescient), diminished night time imaginative and prescient, and issue adjusting between mild and darkish environments. These results are believed to stem from S4’s interplay with ocular receptors and usually resolve after discontinuation or dose discount. They’re extremely dose-dependent and extra widespread at 50 mg+/day and longer cycles.
“Andarine’s partial agonism and off-target binding have been linked anecdotally to transient visible disturbances, together with altered shade notion and impaired night time imaginative and prescient, which seem reversible upon cessation.” (Basaria, Journal of Scientific Endocrinology & Metabolism).
→ Testosterone Suppression
Regardless of being marketed as “milder,” S4 suppresses the HPG axis, resulting in lowered endogenous testosterone, diminished libido, lethargy, and potential temper modifications. It is best to plan for PCT with a SERM like Clomid or Nolvadex after most S4 cycles—particularly if stacked or run past 6 weeks.
“Nonsteroidal SARMs can considerably suppress endogenous testosterone and require post-cycle methods to re-establish HPG axis operate.” (Alves et al., Asian Journal of Andrology).
→ Lipid Dysregulation
Like many oral anabolics and SARMs, S4 can decrease HDL and lift LDL, growing long-term cardiovascular danger if abused or run repeatedly with out monitoring.
“SARM utilization has been related to opposed lipid transforming, together with decreased HDL and elevated LDL, much like oral AAS.” (Rahnema et al., Mayo Clinic Proceedings).
→ Liver Enzyme Elevations
Though S4 isn’t a 17α-alkylated steroid, hepatotoxicity and elevated liver enzymes have been reported throughout the SARM class—usually compounded by product contamination or mislabeling in gray-market sources.
“Unapproved SARM merchandise have been implicated in liver damage and different severe opposed occasions.” (Garey et al., LiverTox / NIH).
→ Temper, Libido, and Power Swings
Suppression, altered neurotransmitter signaling, and lipid modifications can drive temper instability, libido fluctuations, and power crashes—usually changing into most noticeable post-cycle if PCT is skipped or poorly executed. See our SERM overview: Selective Estrogen Receptor Modulators (SERMs).
→ Visible Facet Results Throughout Driving or Night time Coaching
As a result of impaired darkish adaptation, customers ought to pay attention to potential security dangers whereas driving at night time or coaching in low-light environments. If visible sides change into problematic, scale back the dose or discontinue.
S4 (Andarine) Dosage, Cycle Size, and Tips on how to Use It Safely
Operating an S4 cycle requires extra than simply selecting a dose and hoping for outcomes. Due to its quick half-life, suppression danger, and distinctive facet impact profile, timing, dosing technique, and post-cycle planning are important. This isn’t a compound to “dabble” with—get it fallacious, and you could possibly find yourself with hormonal crash, visible impairment, or each.
→ Customary S4 Dosage Vary
Typical S4 doses vary from 25–50 mg per day, cut up into two doses because of the 3–6 hour half-life.
→ Rookies: 25 mg/day cut up into 12.5 mg AM / 12.5 mg PM
→ Skilled customers: As much as 50 mg/day (cut up AM/PM), however with larger danger of visible sides
→ Feminine customers: Hardly ever really useful attributable to lack of information and danger of virilization
“Andarine has a brief half-life, requiring a number of every day doses to take care of constant plasma concentrations and scale back peak-related uncomfortable side effects.” (Yin et al., Journal of Medicinal Chemistry)
→ Really useful Cycle Size
→ Typical cycle size: 6–8 weeks
→ Superior customers (with PCT plan): as much as 10 weeks
→ Submit-cycle remedy required: Sure — even at decrease doses
S4 is suppressive. In case your cycle exceeds 4 weeks at any dosage, plan to make use of Clomid or Nolvadex for 4 weeks post-cycle.
→ Cycle Instance: 8 Weeks
Weeks 1–4:
→ 25 mg/day cut up into 12.5 mg AM and PM
Weeks 5–8:
→ Improve to 50 mg/day cut up into 25 mg AM and PM (provided that visible sides are manageable)
Weeks 9–12 (PCT):
→ Clomid: 50/50/25/25 mg/day
→ OR Nolvadex: 40/40/20/20 mg/day
→ Finest Practices for Security
→ Begin low and improve provided that imaginative and prescient sides are tolerable
→ Use a split-dosing protocol to easy blood concentrations
→ Keep away from driving at night time if experiencing visible points
→ Get pre- and post-cycle bloodwork (testosterone, LH/FSH, lipids, liver enzymes)
→ By no means use S4 and not using a PCT plan
→ Solely supply from labs that present third-party testing
S4 Stacking Protocols: What Works and What Doesn’t
S4 is simplest in slicing and recomposition stacks the place lean muscle retention and fats loss are priorities. As a result of it doesn’t trigger water retention or aromatize to estrogen, it stacks properly with different dry compounds—but additionally will increase the chance of testosterone suppression, particularly when paired with different SARMs.
Right here’s how S4 is often utilized in stacks, and what to keep away from:
→ Finest SARMs to Stack with S4
→ Ostarine (MK-2866): A gentle SARM for preserving muscle throughout a minimize. Stacking Ostarine + S4 gives a synergistic impact on muscle retention and energy with out extreme suppression (for many customers).
→ Cardarine (GW501516): A PPAR-delta agonist, not a SARM, however glorious for growing endurance, fats oxidation, and stamina throughout cardio-intensive cuts.
→ MK-677 (Ibutamoren): Boosts development hormone and helps enhance restoration, sleep, and fullness throughout calorie deficits. Since MK-677 doesn’t suppress testosterone, it pairs properly with suppressive SARMs like S4.
“Combining SARMs with non-suppressive brokers like MK-677 or Cardarine can assist mitigate fatigue and restoration points with out including to HPTA suppression.” (Rahnema et al., Mayo Clinic Proceedings)
→ Keep away from Stacking with Extremely Suppressive SARMs
→ Stacking S4 with RAD-140 or S23 can result in extreme testosterone shutdown. These stacks are in style on-line—however not really useful except you’re working testosterone base help and planning for a very sturdy PCT.
“Stacking a number of suppressive SARMs with out exogenous testosterone or medical oversight can result in vital endocrine disruption, usually requiring medical intervention.” (Basaria, JCEM)
→ Peptides and Restoration Stack Choices
→ Think about including recovery-focused peptides like:
→ BPC-157 for joint and tendon well being
→ TB-500 for smooth tissue restoration and irritation management
→ CJC-1295 + Ipamorelin for GH launch and fats loss help throughout minimize cycles
These additions received’t affect testosterone ranges however can drastically enhance restoration and tissue integrity, particularly when coaching quantity is excessive.
Is S4 (Andarine) Authorized?
The authorized standing of S4 is murky—and relies upon totally on the place you reside and the way you propose to make use of it. In the US, S4 will not be accepted for human consumption and is taken into account a analysis chemical. It isn’t a managed substance, however it’s banned for athletic use and infrequently misrepresented in on-line markets.
→ FDA Standing: S4 is not FDA-approved for any medical use and is illegitimate to promote or market as a dietary complement or performance-enhancing drug
→ World Anti-Doping Company (WADA): S4 seems on WADA’s Prohibited Listing, banned out and in of competitors for all athletes
→ USADA Sanctions: Athletes who check optimistic for S4 face suspensions, fines, and disqualification from competitors
→ Bought as “Not for Human Use”: To bypass regulation, S4 is often labeled as a “analysis chemical” or “lab use solely,” despite the fact that it is broadly utilized in bodybuilding communities
“S4, like all SARMs, is prohibited below the WADA Code and has been linked to a number of anti-doping violations throughout a spread of sports activities.” (WADA, Prohibited Listing)
As a result of SARMs should not scheduled substances below federal legislation, possessing them isn’t essentially against the law—however shopping for, promoting, or utilizing them exterior of analysis contexts is a authorized grey zone. Worse, many merchandise are underdosed, contaminated, or spiked with steroids, making third-party testing important.
In case you’re contemplating options, discover authorized compounds like DHEA, MK-677, or restoration peptides like BPC-157 and TB-500.
Frequent Newbie Errors with S4 (Andarine)
S4 is usually marketed as a “gentle” SARM, which leads many first-time customers to underestimate how severe the uncomfortable side effects and suppression may be. Beneath are the commonest errors newbies make—and the right way to keep away from them.
→ Mistake #1: Beginning at Too Excessive a Dose
Many newbies leap straight to 50 mg/day or extra, chasing quick outcomes. This considerably will increase the chance of imaginative and prescient uncomfortable side effects, testosterone suppression, and liver stress. At all times begin low (e.g., 25 mg/day cut up into two doses) and assess tolerance earlier than growing.
→ Mistake #2: Ignoring Imaginative and prescient Signs
S4’s visible sides (yellow tint, night time blindness) are distinctive to this SARM and are sometimes dismissed. However persevering with to extend the dose whereas imaginative and prescient points worsen may be harmful. If sides seem, scale back your dose or take a break—don’t attempt to “push by way of it.”
→ Mistake #3: Operating With out PCT
Even quick cycles of S4 can suppress testosterone. Skipping PCT results in libido crashes, temper swings, and muscle loss. A 4-week SERM protocol utilizing Clomid or Nolvadex is obligatory for correct restoration.
→ Mistake #4: Utilizing Low-High quality or Mislabeled Merchandise
The S4 market is unregulated, and most merchandise bought on-line are not lab-tested. Some are underdosed, spiked with steroids, or not S4 in any respect. At all times confirm third-party testing or keep away from altogether.
“In a 2022 examine of 44 SARM merchandise bought on-line, solely 52% contained any energetic SARM, and 39% contained different unapproved medication or steroids.” (Evans-Brown et al., BMJ)
→ Mistake #5: No Bloodwork, No Plan
Utilizing S4 with out figuring out your baseline testosterone, lipids, or liver enzymes is reckless. Observe your markers earlier than, throughout, and after your cycle to handle danger and restoration correctly.
Conclusion
S4 (Andarine) is usually promoted as a gentle, side-effect-free SARM very best for newbies—however that popularity may be dangerously deceptive. Whereas it could ship noticeable fats loss, muscle hardness, and vascularity, it additionally comes with actual dangers: suppression, liver pressure, and the notorious imaginative and prescient uncomfortable side effects that no different SARM shares.
→ It really works properly for slicing and recomposition, particularly when paired with compounds like MK-677 or Cardarine
→ However and not using a PCT plan, bloodwork, and sourcing from a trusted vendor, the dangers usually outweigh the rewards
→ In case you’re severe about long-term efficiency and well being, think about safer options like DHEA, BPC-157, or recovery-focused peptides to reinforce your outcomes legally and responsibly
S4 is not for the curious. It is for the knowledgeable. In case you’re not ready to deal with it like a severe hormone-altering compound, you are not prepared to make use of it.
Prepare arduous. Get well good. And if you are going to improve—do it with readability, construction, and a post-cycle plan.