Human Chorionic Gonadotropin
Human chorionic gonadotropin (hCG) is a glycoprotein hormone that mimics luteinising hormone (LH), directly stimulating the Leydig cells of the testes to produce testosterone. It is used to maintain testicular size and function during suppressive cycles and as part of HPTA restart, preventing or reversing the testicular atrophy that exogenous androgens cause.
01 Overview
Because hCG binds and activates the LH receptor, it bypasses a suppressed pituitary and drives the testes directly. On suppressive cycles it keeps the testes responsive and preserves intratesticular testosterone and volume, which makes subsequent recovery easier; in fertility settings it stimulates spermatogenesis, sometimes combined with FSH.
The main hazards are over-stimulation and excess aromatisation: high or frequent dosing raises intratesticular oestrogen, can desensitise Leydig cells, and paradoxically impair recovery. Low, regular dosing during a cycle is generally preferred to large blast doses. It is injected subcutaneously or intramuscularly and dosed in international units.
02 Mechanism
Acts as an LH analogue, binding testicular LH receptors to stimulate Leydig-cell testosterone production and maintain testicular volume and spermatogenic support.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| On-cycle maintenance | 250–500 IU/wk | SubQ | Often split into 2-3 injections weekly (e.g. 250 IU twice weekly) to preserve testicular function. |
| HPTA restart / stimulation | 1500–5000 IU/wk | SubQ | Higher stimulation doses (e.g. 1500-2500 IU 2-3x/week) before or during PCT; excess raises intratesticular oestrogen. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Maintained testicular size/functionDirectly stimulates Leydig cells, preserving testicular volume and intratesticular testosterone during androgen suppression. | prevents atrophy | Clinical | |
| Supports spermatogenesisRestores or maintains sperm production in secondary hypogonadism, sometimes with added FSH. | improved fertility | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Excess aromatisation / high oestradiolStrong Leydig-cell stimulation raises intratesticular and systemic oestradiol, causing water retention or gynaecomastia. | Moderate | Common at high doses | Clinical | |
| Leydig-cell desensitisationProlonged high-dose use can down-regulate the LH-receptor response, blunting recovery. | Moderate | Uncommon | Observational | |
| Injection-site reactionsLocal redness, swelling or discomfort at the injection site. | Mild | Common | Clinical |
06 Commonly used with
What human is combined with, and why. This is about intent rather than safety — the interactions table below covers what is dangerous. Nothing here is listed without what it costs.
| Compound | Frequency | Purpose & trade-off |
|---|---|---|
| Support & ancillaries | ||
| Testosteroneon-cycle | Run alongside suppressive testosterone to maintain testicular size and function and ease later recovery.Trade-off: hCG drives intratesticular aromatisation, raising estrogen and often forcing an AI alongside it. | |
| Anastrozoleestrogen control | Paired with an AI to offset the estrogen surge hCG causes through stimulated testicular steroidogenesis.Trade-off: Balancing hCG-driven estrogen against an AI is finicky and easily overshoots into a crash. | |
| Trenboloneon-cycle | Added to heavily suppressive 19-nor cycles to preserve testicular responsiveness that would otherwise shut down hard.Trade-off: hCG cannot prevent the deep central suppression of such cycles and can desensitise Leydig cells if overused. | |
| Post-cycle | ||
| Clomifenepre-PCT | Used to restore testicular volume before handing off to a SERM that stimulates the pituitary in PCT.Trade-off: Running hCG too close to PCT keeps the axis suppressed and raises estrogen going into recovery. | |