Like other AAS, drostanolone is an agonist of the androgen receptor (AR).  It is not a substrate for 5α-reductase and is a poor substrate for 3α-hydroxysteroid dehydrogenase (3α-HSD), and therefore shows a high ratio of anabolic to androgenic activity.  As a DHT derivative, drostanolone is not a substrate for aromatase and hence cannot be aromatized into estrogenic metabolites .  While no data are available on the progestogenic activity of drostanolone, it is thought to have low or no such activity similarly to other DHT derivatives.  Since the drug is not 17α-alkylated , it is not known to cause hepatotoxicity . 
Masteron will significantly suppress natural testosterone production making exogenous testosterone therapy important when using this steroid. Failure to include exogenous testosterone will lead most men to a low testosterone condition, which not only comes with numerous possible symptoms but is also extremely unhealthy.
As most will use Masteron in a cutting cycle, it’s very common not to want to use a lot of testosterone due to the high levels of estrogenic activity it can provide. If this is the case, you will find a low dose of 100-200mg per week of testosterone to be enough to combat suppression and give you the needed testosterone.
Once Masteron is discontinued and all exogenous steroidal hormones have cleared your system, natural testosterone production will begin again. Prior levels will not return to normal over night, this will take several months. Due to the slow recovery, Post Cycle Therapy (PCT) plans are often recommended. This will speed up the recovery greatly; however, it won’t bring your levels back to their peak, this will still take time. A PCT plan will ensure you have enough testosterone for proper bodily function while your levels continue to naturally rise and significantly cut down on the total recovery time. This natural recovery does assume no prior low testosterone condition existed. It also assumes no damage was done to the Hypothalamic-Pituitary-Testicular-Axis (HPTA) through improper supplementation practices.