Use of hCG to kickstart natural testosterone is problematic and a balancing act. Using hCG for too long a period of time, or in doses that are excessively high, can block the natural production of luteinising hormone (LH) or desensitize the testicles to the effects of LH.

The side effects from HCG use include gynecomastia, water retention, and an increase in sex drive, mood alterations, headaches, and high blood pressure. The main side effects are fluid retention and swelling, joint pains and carpal tunnel syndrome. HCG Pregnyl raises androgen levels in males by up to 400% but HCG Pregnyl also raises estrogen levels dramatically as well. This is why it can cause a real case of gynecomastia if dosages of Pregnyl HCG get too elevated for that person. Another side effect seen from HCG use is morning sickness (nausea and vomiting). There have been no cases of overdose complications with the use of HCG nor have there been any associated carcinomas, liver or renal impairment.