Human Chorionic Gonadotropin (HCG) is a glycoprotein hormone (MW ~36,700 g/mol) composed of an alpha subunit (shared with LH, FSH, TSH) and a unique beta subunit. Naturally produced by placental trophoblasts during pregnancy, pharmaceutical HCG binds LH/CG receptors in the gonads, stimulating testosterone production in Leydig cells and progesterone in the corpus luteum. It is FDA-approved for multiple reproductive indications and is widely used off-label to maintain testicular function during testosterone replacement therapy (TRT).
Category: Hormonal / Reproductive. Evidence rating: A (strong human clinical data).
Clinical status: FDA-approved for anovulation/infertility, hypogonadotropic hypogonadism, prepubertal cryptorchidism.
HCG binds to the LH/CG receptor (LHCGR) on Leydig cells and theca cells with high affinity. In males, this stimulates intratesticular testosterone production, spermatogenesis, and maintains testicular volume. In females, it triggers final oocyte maturation and ovulation. The alpha subunit is…
Research base: 0 registered clinical trials and 8 indexed publications reference HCG.
Safety considerations: Common: injection site reactions, headache, fatigue, mood changes; Males: gynecomastia (from estradiol conversion), water retention, testicular discomfort; Females: ovarian hyperstimulation syndrome (OHSS) — potentially serious.
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-07-05.
Exogenous testosterone suppresses LH through negative feedback, causing testicular atrophy and infertility. HCG mimics LH, maintaining intratesticular testosterone production, testicular size, and spermatogenesis despite exogenous testosterone use.
HCG is a prescription medication that is FDA-approved for specific indications. It is legal with a prescription. It is banned by WADA in sports. The FDA also prohibits its marketing for weight loss.
In March 2020, the FDA reclassified HCG as a biologic under the BPCIA, removing it from the list of drugs that 503A pharmacies can compound. Only brand-name products or 503B outsourcing facilities can now provide it.