HCG on TRT: What It Does and When It Is Used

Human chorionic gonadotropin (HCG) is a hormone that structurally resembles luteinizing hormone (LH) and binds to the same receptor. When used alongside testosterone replacement therapy, it substitutes for the LH signal that TRT suppresses, maintaining testicular stimulation and preserving testicular size, intratesticular testosterone, and sperm production. HCG is not FDA-approved specifically for use in TRT protocols but is widely prescribed off-label for this purpose.

Why HCG Is Used With TRT

When exogenous testosterone is administered, the hypothalamic-pituitary axis detects elevated testosterone and reduces GnRH, LH, and FSH secretion. LH drives Leydig cell testosterone production and is required for spermatogenesis indirectly through its effects on Sertoli cells. Without LH, the testes progressively atrophy in size, intratesticular testosterone falls, and sperm production decreases.

Most men on TRT experience some degree of testicular atrophy, a noticeable decrease in testicular volume over months to years of treatment. For some men this is a significant concern; for others it is not. Fertility suppression is a more universal concern for men who have not completed family planning.

HCG injected two to three times per week provides an LH-like signal that prevents or reverses testicular atrophy and maintains spermatogenesis. A 2005 study in Fertility and Sterility randomized men on testosterone enanthate to receive HCG or placebo. The HCG group maintained testicular volume and sperm concentrations, while the placebo group experienced significant reductions in both.

Dosing Protocols

Typical HCG dosing in TRT protocols ranges from 250 IU to 500 IU administered two to three times per week. Some protocols use 1,500 IU once or twice weekly; dosing is individualized based on response.

HCG was historically supplied as Pregnyl or Novarel (extracted from pregnancy urine). These formulations were discontinued by their manufacturers in 2023, creating a supply disruption that shifted most clinical use to compounded HCG from 503B outsourcing facilities.

Subcutaneous injection using a small insulin syringe is the standard administration route, similar to the technique used for semaglutide or other injectable medications.

HCG as Monotherapy for Secondary Hypogonadism

In men with secondary hypogonadism who want to maintain fertility and avoid exogenous testosterone, HCG monotherapy is an alternative. By directly stimulating Leydig cells, HCG raises endogenous testosterone production without suppressing the HPG axis the way exogenous testosterone does.

Response to HCG monotherapy: testosterone levels typically reach the mid-normal range (400-700 ng/dL) in men with secondary hypogonadism. The testosterone produced comes from the testes themselves, so it is physiologically produced rather than exogenous. FSH production is not directly affected by HCG, so spermatogenesis may still require supplemental FSH if fertility is the primary goal.

HCG monotherapy does not work in primary hypogonadism, where the testes themselves cannot respond to stimulation. It requires a functioning hypothalamic-pituitary connection (the pituitary is bypassed, but the testes must still respond to HCG’s LH-like signal).

Side Effects and Considerations

HCG raises both testosterone and estradiol, because increased intratesticular testosterone leads to increased aromatization. Some men experience gynecomastia or mood changes from elevated estradiol on HCG-inclusive protocols. Monitoring estradiol is appropriate when adding HCG to a TRT regimen.

HCG also stimulates the prostate through its testosterone-raising effect, similar to TRT itself. Men with prostate conditions should discuss HCG use with a urologist.

Gonadorelin as an Alternative

Gonadorelin is a synthetic GnRH that, when dosed at short intervals (subcutaneous injection several times per week), can maintain pituitary LH and FSH secretion during TRT. It is pharmacologically distinct from HCG, rather than directly stimulating the testes, it stimulates the pituitary to produce LH and FSH, which then stimulate the testes.

Some newer TRT protocols use gonadorelin as an HCG alternative, particularly given the HCG supply disruption following the Pregnyl/Novarel discontinuation. The evidence base for gonadorelin in TRT settings is smaller than for HCG.

For more on how fertility is affected by TRT without HCG, see Testosterone and Fertility: What TRT Does to Sperm Production. For an overview of TRT side effects broadly, see TRT Side Effects: What the Research Actually Shows.