Other significant adverse effects of testosterone supplementation include acceleration of pre-existing prostate cancer growth in individuals who have undergone androgen deprivation; increased hematocrit , which can require venipuncture in order to treat; and, exacerbation of sleep apnea .  Adverse effects may also include minor side-effects such as acne and oily skin, as well as, significant hair loss and/or thinning of the hair, which may be prevented with 5-alpha reductase inhibitors ordinarily used for the treatment of benign prostatic hyperplasia , such as finasteride .  Exogenous testosterone may also cause suppression of spermatogenesis , leading to, in some cases, infertility.  It is recommended that physicians screen for prostate cancer with a digital rectal exam and prostate-specific antigen (PSA) level before starting therapy, and monitor PSA and hematocrit levels closely during therapy. 
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.