Andarine, which is also known as S4 or GTx-007, is a selective androgen receptor modulator (SARM) that was developed by GTX Inc – also the developer of Ostarine – to treat a variety of conditions including muscle wasting, osteoporosis and prostatic hypertrophy (enlargement of the prostate).

S4 Andarine Molecule
S4 Andarine Molecule (C19H18F3N3O6)

In the previous articles on OstarineLigandrol and RAD 140, we have touted the anabolic potential of these new compounds for athletic performance and aesthetics, but we have also been at pains to ensure you understand that they have specific uses that will some suit individuals and contexts more than others. That caveat applies here too.

If you put S4 Andarine to the right uses, you will see positive results, with fewer of the side effects associated with the use of performance-enhancing substances like steroids. 

You must, however, be in no doubt of the potential risks and side effects, which we will discuss below.


As an another anabolic SARM, like OstarineLigandrol and RAD 140, Andarine is generally used by bodybuilders, strength athletes (powerlifters, Olympic lifters, strongmen), practitioners of contact sports, martial artists and gymbros. The benefits of Andarine are:

  • Increased lean muscle mass (including during a calorie deficit) and therefore strength
  • Increased energy levels
  • Increased bone strength 
  • Decreased body fat

Andarine, as a SARM with performance-enhancing effects, is listed as an S1 Anabolic Agent on WADA’s prohibited list. In our articles on Ostarine and Ligandrol, we have used lists of athletes who have been banned for using those substances, in order to illustrate their respective properties.

In the case of S4 (Andarine), like RAD 140, it is much harder to find evidence of athletes who have been banned or received sanction for using the substance.

S4 (Andarine) and RAD 140 both seem to be less well known than Ostarine and Ligandrol; although that is not necessarily reason to assume that Ostarine and Ligandrol are the best or better SARMs than Andarine and RAD 140.

Among the cases we could readily find were those of Kayle Leogrande, a cyclist banned for testing positive for Andarine among other substances, and the Australian horse trainer Stuart Gower, who received a sanction when the horse Saturday Sorcerer tested positive for S4 (Andarine) after its win in the Darwin Cup.

There have been no clinical human trials on S4 Andarine. It is regarded as being weaker than other SARMs like Ostarine and Ligandrol and is usually stacked with other SARMs to increase its effects. We will discuss how to stack SARMs in a separate article. 

In addition to its anabolic properties, S4 (Andarine) is touted as one the best SARMs for fat loss, based on clinical trials in rats, which showed a significant decrease in body fat [R].

S4 (Andarine) has a unique side effects among SARMs in that many users report altered vision. We will discuss this side effect later.

SARMs induce anabolic activity – growth – by directly stimulating the body’s androgen receptors. These are specific sites within the body to which androgenic (i.e. male) hormones, including testosterone and androsterone, bind. 

The activity of these androgen receptors, and the binding of androgens to them, is crucial to the proper expression of male characteristics, including muscle growth and reproductive function.

In the womb, androgens are responsible for sexual differentiation, and then during puberty they regulate the development and function of the penis, prostate and other sexual organs, as well as inducing growth spurts, larynx development and growth of skeletal muscle.

For adults, androgens regulate behaviour, the production of sperm, muscle growth, bone function and aspects of the cardiovascular system. Androgens regulate sexual function and are responsible, in part, for aggressive behaviour in men. As a result, disregulation or blocking of the androgen receptors can lead to all sorts of conditions. 

S4 (Andarine) binds to the androgen receptors and mimics the effects of testosterone, increasing protein synthesis and therefore muscle growth.

This is also what steroids do, but SARMs generally have an advantage over steroids, because they only bind to receptors in skeletal muscle tissue. Steroids, by contrast, work on other tissues in the body and have, as a result, been linked to all sorts of side effects, including prostate and heart problems.

SARMs are also non-aromatising, meaning that they aren’t converted to estrogen by the body in an attempt to maintain the body’s testosterone-to-estrogen balance.


By contrast, aromatisation can occur when using steroids or testosterone injections, which upset that balance, leading to problems such as gynecomastia (formation of breast tissue).

Although there is no certified research on the use of this SARM for bodybuilding purposes, research in other contexts indicates that Andarine has the potential to enhance lean muscle mass growth [R]. 

To date, however, there have been no human clinical trials involving Andarine.

Generally, because it is considered to be weaker than Ostarine or Ligandrol users stack Andarine with other SARMs, such as RAD 140, for bulking, increasing strength, cutting and body recomposition. We will discuss SARMs stacks in detail in a separate article.

One Reddit user writes of his S4 (Andarine) cycle:

‘In these 6 weeks I lost 8 pounds of fat and was able to hold on to my muscle much better then [sic] I would have without S4. Vascularity was insane around week 3-4. S4 did exactly what I expected from months of researching and reading logs on here.’

Here the main benefits were clearly fat loss, muscle retention and increased vascularity.

Another user said that he preferred Andarine to Ostarine, although Ligandrol is his favourite SARM.

‘I’ve done both osta and lgd as well as s4. In my opinion S4 is slightly better than ostarine and the reason for that is I felt more strength increase from it which also included more vascularity. However, LGD was my first cycle ever and I prefer that over any other sarm. I like it enough that I am going to run a mini bulk cycle at 6mg per day for 6 weeks and then a mini cut at 3mg per day. Yes, I am going to try LGD lower mg for a cut cycle. I’m interested to see how it compares at 3 mg vs 50mg s4 and 20mg osta.’

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