Though Masteron holds a weaker androgenic strength rating than Testosterone itself, androgenic side effects are still indeed possible with this compound, especially among those who may be particularly sensitive. Masteron side effects that include androgenic side effects include: an increase in oily skin (as a result of increased sebum production/secretion), increased facial hair and bodily hair growth, as well as the increased risk of triggering MPB (Male Pattern Baldness) in those that are genetically sensitive or predisposed to it. Virilization (the development of male characteristics in women) is also a risk with female use, though its use in female breast cancer patients should attest to its acceptable nature as a female-use compound.
First and foremost, it is important to mention that there is no risk what so ever of any Estrogen related side effects from Masteron Enanthate alone. As mentioned previously, Masteron Enanthate not only avoids aromatization into Estrogen completely, but it even acts as an anti-Estrogen in many cases. Therefore, the typical estrogenic side effects that result from the use of aromatizable anabolic steroids is avoided. This includes: bloating, water retention, blood pressure increases (as a result of water retention), acne, and gynecomastia. Because of Masteron’s anti-estrogenic properties, it can actually help prevent or mitigate these side effects if they are occurring from other anabolic steroids that do aromatize.
Drostanolone propionate is a prodrug of drostanolone .  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 .