HCG
Glycoprotein hormone with LH-like activity, structurally homologous to luteinizing hormone
- Class
- Gonadotropin
- Half-life
- ~24-36 hours
- Route
- Subcutaneous (SubQ)
- Cadence
- Multiple per week
- Evidence
- Human clinical trials
Overview
HCG is a hormone your body makes during pregnancy, but in men it works as a stand-in for luteinizing hormone (LH) — the signal from your pituitary that tells your testicles to make testosterone. The catch: unlike testosterone replacement therapy, HCG keeps your own production running. That means preserved fertility, maintained testicular size, and endogenous testosterone production instead of shutting down your natural system.
It's FDA-approved for hypogonadotropic hypogonadism (the kind where your pituitary doesn't make enough LH) and for inducing ovulation in women, but the biggest off-label use is fertility preservation in men on testosterone therapy. Exogenous testosterone — whether injected, topical, or pellet — suppresses LH and FSH within weeks, tanking intratesticular testosterone (normally 50-100× higher than blood levels) and shutting down sperm production. HCG bypasses that suppression by acting directly on the Leydig cells in your testes.
The trade-off: it's more complex than straight testosterone therapy. Most protocols dose 500-3,000 IU two to three times per week via subcutaneous injection. Recovery of spermatogenesis after testosterone-induced azoospermia takes months — median 3-4 months to hit clinically useful sperm counts, but some men take a year or more. Adding FSH (follicle-stimulating hormone) on top of HCG speeds things up and improves success rates, especially in men with very low baseline testicular volume or prepubertal-onset hypogonadism.
Safety considerations
A few of the safety signals worth knowing — the full list, with dosing context and what to monitor, is inside AIx Core.
- FDA-approved for hypogonadotropic hypogonadism and female ovulation induction, but most male use is off-label (fertility preservation during TRT, post-steroid recovery).
- Gynecomastia is the most common side effect — HCG increases both testosterone and estradiol via aromatisation, and the estrogen spike can cause breast tissue growth. An aromatase inhibitor is sometimes co-prescribed.
- Polycythemia (elevated red blood cell count) is less common than with TRT but can still happen, especially at higher doses or when stacked with testosterone.
+ 3 more safety notes inside AIx Core →
Commonly monitored
Markers and signals people track when researching HCG.
- Serum testosterone (total and free) — HCG raises it, but the response is individual
- Semen analysis (volume, concentration, motility) if fertility is the goal
- Testicular volume — should stay stable or increase on HCG, shrinks on TRT alone
- Estradiol — HCG stimulates aromatase in Leydig cells, can push E2 higher than TRT alone
- Hematocrit — less of a concern than with TRT, but still check periodically
- Subjective energy, libido, and mood — the whole reason most people are treating hypogonadism in the first place
Frequently asked questions
What is HCG?
Glycoprotein hormone with LH-like activity, structurally homologous to luteinizing hormone. HCG is a hormone your body makes during pregnancy, but in men it works as a stand-in for luteinizing hormone (LH) — the signal from your pituitary that tells your testicles to make testosterone. The catch: unlike testosterone replacement therapy, HCG keeps your own production running. That means preserved fertility, maintained testicular size, and endogenous testosterone production instead of shutting down your natural system.
How is HCG administered?
Subcutaneous (SubQ), typically multiple per week.
What is the half-life of HCG?
~24-36 hours — Longer than native LH — supports 2-3x weekly dosing instead of continuous.
Is HCG approved for human use?
HCG is investigational — not approved by the FDA, EMA, or MHRA for human use at the time of writing.
What does the evidence show for HCG?
Evidence tier: Human clinical trials. Coviello et al. (J Clin Endocrinol Metab 2005, n=29): 500 IU HCG every other day maintained normal intratesticular testosterone in healthy men suppressed by 200 mg/week testosterone enanthate. Lower doses (125-250 IU) were not sufficient.
What is commonly monitored when researching HCG?
Commonly tracked markers + signals: Serum testosterone (total and free) — HCG raises it, but the response is individual, Semen analysis (volume, concentration, motility) if fertility is the goal, Testicular volume — should stay stable or increase on HCG, shrinks on TRT alone, Estradiol — HCG stimulates aromatase in Leydig cells, can push E2 higher than TRT alone, Hematocrit — less of a concern than with TRT, but still check periodically, Subjective energy, libido, and mood — the whole reason most people are treating hypogonadism in the first place.
Related compounds
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Mechanism breakdown, receptor pathway diagram, full safety list, monitored items, source citations, and one-tap add-to-protocol. Free with any account.