S4 (Andarine)

S4 (Andarine)S4 is also called Andarine or Acetamidoxolutamide. It is a type of SARMs (Selective Androgen Receptor Modulator) that is marketed as a potent muscle mass developer whilst being able to strip fat at the same time. Enough of the science lesson, now let’s see what this bad boy performing enhancing drug (PED) is all about…

The benefits of S4

  • Very limited growth on tissues of the major organs e.g. prostate, heart, liver and kidneys
  • There is no significant change in the LDL/HDL ratio- this makes it is very low cardiovascular risk
  • No chance of female characteristics e.g. man boobs, developing in the post cycle recovery stage
  • There is no reduction in testosterone during the post cycle recovery
  • It does not require a lengthy post cycle recovery- 4 weeks is a good time span
  • It increases muscle mass and reduces % body fat.

Buy Andarine (S4)

What is S4?

OK- we may have to throw a little more science thrown in to the mix, so that you get a clear understanding of how SARMs actually work. There are 3 different types of ‘chemicals’ that bind with the androgen receptors, these are as follows:

  1. The androgen receptor ‘antagonists’ prevent the chemicals from activating
  2. ‘agonists’ helps the chemicals to bind and detach e.g. testosterone
  3. ‘modulators’ changes its structure and can react in different way.

S4 attaches itself to the androgen receptors and sticks to it like glue. This process exclusively creates more bone and muscle tissue growth.  Therefore S4 is a type of SARMs that does attach itself to androgen receptors; this is very similar to other performance enhancing drugs. The only difference is that S4 is extremely selective about its anabolic activity. Let’s take this a step further…

Further understanding

We have established that SARMs work by binding themselves to androgen receptors and this is a major a catalyst for anabolic activity within the body.  During this process more anabolic hormones are released and more protein can be utilised as building blocks. This triggers an increase in muscle mass, which is good news if you are on the gain’s train! The process is very similar to the way that steroids work but without the nasty side effects (the side effects of S4 will be discussed further on in the article).

Andarine has a very high androgenic impact on the body. Studies have shown that it has about 30% of the overall strength of testosterone when binding to the androgen receptors (1). Therefore S4 boosts the amount of muscle gains by desensitising the androgen receptors. This in turn frees up the testosterone to perform its anabolic magic e.g. building new muscle tissue and burning body fat.  Are we loving the benefits of S4 so far?

Major research

Andarine is probably the most researched type of SARMs on the performance enhancing drug market. After the discovery of its anabolic properties, the main objective of many of the studies was to develop a different treatment for age-related diseases such as muscle wasting, osteoporosis and hypogonadism.

Apart from maintaining lean muscle tissue, S4 actually helps to boost it. A study reported an increase of 1-1.5 kg of muscle mass in 90 days, with no increase in daily exercise or a significant change in diet (2). In addition that was also a decrease in % body fat reported and this was attributed to S4’s ability to break down stored fatty tissue (2). No side effects were reported such as liver damage, man boobs or unwanted hair growth- which is always a bonus!

s4 (Andarine) studies on lean mass, fat mass and bodyweight

Body composition change between 12 (before S-4 and DHT treatment) and 20 wk (after S-4 and DHT treatment) after ORX


S-4 (3 and 10 mg/kg) and DHT (3 mg/kg) restored castration-induced loss in lean body mass. Furthermore, S-4 treatment caused a significantly larger increase in total body bone mineral density than DHT. S-4 (3 and 10 mg/kg) also demonstrated agonist activity in the pituitary and significantly decreased plasma LH and FSH levels in castrated animals in a dose-dependent manner.

When to use Andarine


Andarine properties are very similar to the steroids Anavar and Winstrol; however it is well documented that S4 does produce better gains. There is anecdotal evidence that some bodybuilders can produce up to 1kg of muscle mass when they are in calorie deficit.

In terms of fat burning S4 does reduce lipoprotein lipase which is an enzyme that plays a major role in storing fat. S4 breaks down the stored fat and it is then used as an energy source when training. This reduction in % body fat can also improve vascularity and this bolsters that chiselled appearance. S4 produces no significant water retention and no painful joints when pumping iron- again this speaks volumes to any serious lifter!


Realistically Andarine is probably not the first SARMs on the list, when you are thinking about bulking up. LGD4033 and RAD 140 are better bulking agents than Andarine. However S4 can utilise the extra consumption of calories that are often consumed when bulking up. You will not only bang on extra muscle gains, but it you will remain lean at the same time. This is good news if you are looking for that lean summer looking physique that chicks dig!

Side effects

The big hitter when taking Andarine is that it can cause issues within the eyes. A lot of individuals report altered colour perception and night time blindness. The main cause of this is S4 binding to the eye receptors. However, these conditions are not permanent and eyes will return back to their normal state of health.


If you do decide to give S4 a shot- then consume 2 x 25mgs doses on a daily basis for 12-16 weeks. S-4 does not need to be taken on 3 separate occasions throughout the day. Try to consume S4 with main meals. Complete a 4 week cycle and give your body a 4 week flush before starting another cycle.

In terms of gaining muscle Andarine does have a diminishing point. If you daily dose over 75 mgs for more than 16 weeks, this will have no significant impact on your gains. There will be no added side effects at higher does. But you do run the risk of lowering the amount of free testosterone during the post cycle flush!

Andarine does seem to work more effectively when combined with other types of SARMs. Fundamentally it does work well with both MK-2866 and LGD 4033. Both of these SARMs suppress testosterone levels at higher dosages and S4 does seem to stop this from happening.

Is it banned?

Andarine was extremely popular before the Beijing Olympics in 2008. In 2008 SARMs were ultimately banned for professional athletes by WADA. However, if you an amateur bodybuilder and want to pack on some muscle mass; get lean without damaging your health…then why not give S4 a go!


(1) Narayanan, R., Mohler, M. L., Bohl, C. E., Miller, D. D., & Dalton, J. T. (2008). Selective androgen receptor modulators in preclinical and clinical development. Retrieved September 27, 2016, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2602589

(2) Otto-Duessel, M., He, M., Adamson, T. W., & Jones, J. O. (2013). Enhanced Evaluation of Selective Androgen Receptor Modulators In Vivo. Retrieved September 27, 2016, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3910424/

(3) Further Reading on S4 (Andarine)

Andarine (S4)



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