HCG
Human Chorionic Gonadotropin · Choragon
Human chorionic gonadotropin; mimics LH, used on-cycle and in PCT to preserve testicular function.
Key takeaways
- Approved gonadotropin that mimics LH, stimulating testicular testosterone production directly at the Leydig cell.
- ~47-hour half-life after SubQ injection; 2–3 doses per week sustain stable levels.
- Clinical dosing runs 1,500–5,000 IU 2–3× weekly; community on-cycle doses are far lower and anecdotal.
- High doses raise estradiol and can desensitize Leydig cells — more is not better.
Overview
What it is
Human chorionic gonadotropin (hCG) is a placental glycoprotein hormone that mimics luteinizing hormone. It binds LH receptors on testicular Leydig cells, driving endogenous testosterone production, which is why it appears in fertility treatment, TRT-adjunct protocols, and post-cycle recovery.
Pharmacokinetics
After subcutaneous injection, hCG has a roughly 47-hour half-life, peaks around 24 hours, and shows about 45% bioavailability, so two to three injections per week sustain a stable LH-mimetic signal. Doses are discussed in IU: the dataset's 0.5 mg default is roughly 5,000 IU (100 IU ≈ 0.01 mg).
What the evidence says
hCG is an approved drug with decades of human use in hypogonadotropic hypogonadism and fertility treatment. The on-cycle and PCT applications common in community use are extrapolations of that physiology rather than trial-tested protocols. High doses raise estradiol and can desensitize Leydig cells.
Reported dosing protocols
Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.
| Use case | Dose | Route | Frequency | Duration |
|---|---|---|---|---|
| Hypogonadism / fertility (clinical) | 1,500–5,000 IU (0.15–0.5 mg) | SubQ or IM | 2–3× weekly | Weeks to months |
| On-cycle testicular support (community) | 250–500 IU | SubQ | 2–3× weekly | Duration of cycle |
Pharmacokinetic summary
- Model tier
- Advanced (t½ + Cmax + Tmax + F)
- Half-life
- 47.1 hours
- Cmax
- 2072 mIU/mL
- Tmax
- 1.0 days
- Bioavailability
- 45%
- Typical dose
- 0.25–1 mg
Frequently asked questions
Does hCG replace PCT?
No. hCG stimulates the testes directly but keeps the hypothalamic-pituitary axis suppressed. It can preserve testicular function during suppression, but restarting the axis itself takes a SERM-based protocol after exogenous hormones clear.
Why do hCG doses vary so much between sources?
Clinical labels for hypogonadism run 1,500–5,000 IU several times weekly, while community on-cycle protocols use 250–500 IU. The low end aims to maintain testicular function without spiking estradiol; neither end has head-to-head trial data.
Can hCG desensitize the testes?
Yes. Sustained high-dose exposure downregulates LH receptors on Leydig cells, blunting the testosterone response. That's the pharmacological basis for keeping doses modest and courses time-limited rather than continuous at high doses.
References
- PMC HCG PK — 100 IU ≈ 0.01 mg / 10 μg.
- First-in-human recombinant hCG PK/PD trial (Clin Transl Sci 2021) — Human PK data for recombinant hCG; the dataset models urinary-derived product similarly.
Related articles
Related compounds
HMG (Menotropin)
Human menopausal gonadotropin providing FSH and LH activity; used in PCT and fertility protocols.
Gonadorelin Acetate
Native gonadotropin-releasing hormone; stimulates LH/FSH release. Pulsatile (not continuous) use matters.
Kisspeptin
Neuropeptide that drives GnRH release upstream of the HPG axis; researched for hormone restoration.
Protocols featuring HCG
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