In fact, Mesterolone is actually believed to work as an anti aromatase in the body which means that it is not only not going to offer any estrogen related side effects, but is also going to prevent or slow the conversion of the steroids into the estrogen. The result is going to be somewhat comparable to the very well known anti estrogen Arimidex, however the effects are still going to be less profound since Mesterolone, ultimately, is a steroid and not an anti estrogen. Dihydrotestosterone and Masteron 2-methyl-dihydrotestosteronefor example, have been successfully used as therapies for gynecomastia and for breast cancer because of their strong androgenic and potentially anti estrogenic effect. In addition to that, it also has been suggested the fact that nandrolone may even lower aromatase the activity in peripheral tissues, the area where it is being more resistant to estrogen conversion the most active site of Testosterone Enanthate nandrolone aromatization seems to be the liver. The anti estrogenic activities of all of those substances are presumably being caused by their ability to compete with some other substrates for the binding to the aromatase enzyme. With the aromatase enzyme that is being bound to the steroid, and yet is being unable to alter it, pretty much something like an inhibiting effect is being achieved as it is being temporarily blocked from interacting with some other hormones. With this being said, it is pretty obvious that the steroid is indeed having some possible androgenic side effects. These virilizing side effects are including a deepening of the voice, clitoral enlargement, menstrual irregularities, facial hair growth as well as changes in the skin texture. You should know that in case these side effects do appear, you should discontinue the steroid use at their onset because this way the side effects would most likely disappear very soon without any problems. Plus to everything mentioned, the 5 alpha reductase enzyme is not metabolizing Mesterolone, this means that its relative androgenicity is Testosterone Enan going to be affected by the 5 alpha reductase products like for example Finasteride or Dutasteride. Mesterolone Hepatotoxic Side Effects Mesterolone is a steroid that is taken in form of tablets by mouth and yet, is not a c17 alpha alkylated product, therefore this substance should not offer absolutely any stress to the liver.