HCG - Human Chorionic Gonadotropin - is the active ingredient used in "Pregnyl".
Pregnyl (chorionic gonadotropin) is a hormone used to cause ovulation and to treat infertility in women, and to increase sperm count in men. Human chorionic gonadotropin (HCG) is also used in young boys when their testicles have not dropped down into the scrotum normally.- Human Chorionic Gonadotropin - is the active ingredient used in "Pregnyl".
It is typically used as part of a PCT to "reactivate" ones natural production of testosterone post cycle. When on a heavy, long cycle it is also advisable to use it weekly at a low dose of 250 - 500iu to just keep the testicles active during the cycle. This helps with the "kick start" of natural production at the end of the cycle as the testicle will not be starting from a point of a prolonged period of zero / low activity.