• Increased muscle
  • Increased libido
  • Low side effects



S4 (also known as Andarine) is a SARM developed by the same company who created Ostarine. S4 was created as a male contraceptive and to prevent muscle wastage, osteoporosis and prostate enlargement.

It has been picked up by athletes as a strong compound to create muscle, while lacking many of the side effects usually associated with prohormones and steroids.

S4 has around one-third of the binding affinity of testosterone to the androgen receptor, but also has the effect of making the user’s own testosterone exert a greater effect than normal on protein synthesis and muscle mass. S4 is the most research SARM available, with multiple studies confirming its effects. S4 provides greater muscle building potential than DHT – the strongest male hormone men naturally produce.

While helping to build muscle, one of the side effects is that individuals actually lose body fat.

Actual amount of fat lost is dependant on the genetics of the user, but it increases the body’s ability to oxidise fat. S4 also has the effect of “drying out” the muscle in the same way the anabolic steroid Winstrol would, which means it can be great as a hardener towards the end of a cycle or pre-contest.

S4 is not liver toxic, so a liver support such as milk thistle is not necessary. S4 is a mild anti-oestrogen and will lower oestrogen levels, it has been reported to help prevent gynecomastia (development of male breast tissue).

S4 can best be compared to the steroids Anavar or Winstrol, or the prohormone Halodrol for it’s positive effects on body composition, while lacking all of the side effects of these compounds.

Dosing: S4 should be taken between 25 mg for the first week and 50 mg per day for the second week, then increased to 50-75 mg per day for the remainder of the cycle if possible (the reason for this strange pattern of initial dosing is explained in the next paragraph).

It can be run long term, up to 12 weeks for advanced users, although first time users should use no more than 50 mg for 8 weeks. S4 has a short half life of 3.5-5.5 hours, therefore split dosing is recommended.

Important: S4 can reduce night vision as a side effect or cause a yellow tint to eyesight, this is a common and completely harmless effect, but to reduce this; it is suggested to run S4 5 days per week, with 2 days off. The initial dosing protocol of slowly increasing the dose over the first 1-3 weeks has been reported to minimise the vision issue. It is important that this first 3 week protocol is followed.

PCT: although a SARM, very mild suppression may occur in some individuals, so pct should always be kept on hand if needed. For this, D-aspartic acid may be enough, although to be certain, 50 mg per day of arimistane (Pure Labs Clomadex) use will be very good alongside DAA.




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