Male hormonal contraceptives blocks or are able to severely reduce production of sperm count. These basically targets male hormones what we call testosterone. The hormone secretion in brain and testes are reduced, so sperm production in return slows down or halts. Male hormone contraceptive formulation replaces testosterone with other male characteristics like muscle mass or facial hair. The MHC generally takes 11/2 to 21/2 months to show its efficacy and once spermatogenesis is halted it takes about 21/2 months to produce spermatids, travel through and exit through epididymis.
Frequent injections along with some formulation leads to uneven levels of active androgens, which can lead to side effects like lean muscle, weight gain, increased ache and change in mood. It is important to maintain even level of testosterone in blood as in case of spike of testosterone immediately after injection may lead to reappearance of sperm in male ejaculation. MHC is associated with side effects due to synthetic androgen in MHC. One of the main side effect is reduced level of high density lipoprotein cholesterol (HDL-C), which is necessary to reduce risk of arthrosclerosis in blood.  Males are advised to avoid MHC dose or take under expert supervision to prevent risk of heart