hCG
Human Chorionic Gonadotropin · HCG · Chorionic Gonadotropin · Pregnyl · Novarel · Ovidrel (recombinant hCG)
LH-mimic that keeps the testes producing while exogenous androgens shut the axis down.
Typical dose
500 IU
Every other day, or 2-3x per week
Range
125–4000
IU
Half-life
23 h
see Dosing
Evidence
Human trials
Subcutaneous · Intramuscular
What it is
hCG is a placental glycoprotein hormone that binds the same receptor as LH. Because it acts directly on the Leydig cells in the testes, it bypasses a suppressed hypothalamus and pituitary entirely, which is why it is the standard tool for holding testicular function while testosterone or other androgens are being run.
It is used three ways in this community: alongside TRT or a cycle to maintain testicular volume and intratesticular testosterone, as a short run before PCT to make the testes responsive again before SERMs are started, and as part of a medically supervised fertility protocol together with hMG. Only the first two are common here; the fertility use is a longer, slower project.
The dose that matters is far lower than most people assume. A controlled study in men whose gonadotropins were suppressed by weekly testosterone found that 125 to 500 IU every other day held intratesticular testosterone in or above the normal range, with a clean dose-response. Doses well above that mainly raise estradiol and eventually blunt Leydig cell responsiveness.
How it works
hCG shares an identical alpha subunit with LH and binds the same LH/hCG receptor. Its beta subunit is homologous to LH-beta but distinct, carrying an extra 24-amino-acid C-terminal peptide whose heavy O-linked glycosylation and sialic acid content give hCG a far longer circulating half-life, so a single injection provides many hours of Leydig cell stimulation. Binding the LH/hCG receptor drives steroidogenesis in the testis, restoring intratesticular testosterone, which is the signal Sertoli cells and developing sperm actually depend on.
What hCG does not do is replace FSH. Spermatogenesis needs both LH-type and FSH signalling, so hCG alone will hold testicular volume and often maintain some sperm production, but men who need full quantitative spermatogenesis frequently have to add an FSH source such as hMG.
Dosing
hCG is standardised by bioactivity, so vials are labelled in IU only and there is no reliable mg-per-vial or IU-per-mg figure for urinary hCG (only recombinant choriogonadotropin alfa is mass-labelled), which is why vialSizesMg and iuPerMg are left empty here and the vial strengths are carried in vialSizesIu instead. 250-500 IU every other day is enough to hold intratesticular testosterone; more mostly buys estradiol.
Reconstitution calculator
Pre-loaded with hCG’s vial size, water volume and typical dose. Change anything.
Typical: 500 IU · range 125–4000
Draw to
20 u
0.2 mL · 500 IU
Concentration
2500 IU/mL
25 IU per unit
Doses per vial
10
Vial lasts
3 weeks 2 days
Draw to 20 units on the barrel.
Once mixed
Refrigerate at 2-8 °C and use within about 30 days when reconstituted with bacteriostatic water; potency drifts down after that and falls quickly if the vial is left at room temperature.
A 5,000 IU vial in 2 mL of bacteriostatic water gives 2,500 IU/mL, so 500 IU is 0.2 mL, or 20 units on a U-100 insulin syringe. Aim the water down the vial wall and swirl gently: hCG is a fragile glycoprotein and shaking or foaming it degrades potency.
Storage
Before mixing
Stable at room temperature below 25 °C protected from light for the labelled shelf life; refrigeration at 2-8 °C is better for anything held long term.
After mixing
Refrigerate at 2-8 °C and use within about 30 days when reconstituted with bacteriostatic water; potency drifts down after that and falls quickly if the vial is left at room temperature.
Reported benefits
- ▪Maintains intratesticular testosterone and testicular volume while LH is suppressed
- ▪Preserves spermatogenesis during TRT or a cycle rather than trying to recover it later
- ▪Low doses work: 125-500 IU every other day is validated in a controlled human study
- ▪Often restores libido, ejaculate volume and morning erections that fade on TRT
- ▪Primes the testes before PCT so SERMs have something responsive to work with
- ▪Effect is easy to verify on bloods as rising total testosterone and estradiol
Side effects
- ▪Estradiol rises steeply, bringing gyno risk, water retention and mood swings
- ▪Leydig cell desensitisation at high or over-frequent doses, which defeats the purpose
- ▪Acne and oily skin as Leydig cell stimulation raises serum testosterone and DHT
- ▪Injection-site soreness and occasional lumps, worse with IM than subcutaneous
- ▪Progesterone can rise, felt by some men as lethargy or nipple sensitivity
- ▪Does not supply FSH, so sperm counts can stay poor on hCG alone
- ▪Testicular ache in the first week or two as volume comes back
Do not use if
- ▪Androgen-dependent malignancy, including prostate cancer
- ▪Known hypersensitivity to gonadotropin preparations
- ▪Untreated or active pituitary and hypothalamic tumours
- ▪Precocious puberty
- ▪Uncontrolled high estradiol or active gynecomastia without an AI or SERM in place
Evidence level — Human trials
Controlled human clinical data exists.
Prescription-only in most markets, approved for hypogonadotropic hypogonadism, cryptorchidism and fertility induction, with widespread grey-market and research-chemical supply alongside the licensed product.
Commonly run with
hCG FAQ
How much hCG do I actually need on cycle or on TRT?+
250-500 IU every other day covers almost everyone. The Coviello study found 125 IU every other day left intratesticular testosterone about 25 percent below baseline and 500 IU put it about 26 percent above baseline — both still inside the normal range, which was the study's whole point: low-dose hCG keeps ITT normal, it does not mean more is better. Running 1,000 IU or more several times a week is mostly an estradiol problem with no extra testicular benefit.
Subcutaneous or intramuscular?+
Subcutaneous into abdominal fat with an insulin syringe is the norm and works fine; the licensed labelling is IM largely for historical reasons. Subq is less painful, easier to dose accurately in small volumes and produces comparable blood levels.
Will hCG on its own fix my sperm count?+
Often it maintains it, but recovering it from zero is a different job. hCG replaces LH signalling only, and full quantitative spermatogenesis also needs FSH, which is why hMG or recombinant FSH gets added when hCG alone has not produced sperm after several months.
Should I run hCG during PCT?+
Most protocols run it before PCT, not during. hCG keeps the testes working but also suppresses the pituitary through negative feedback, so it is typically stopped once SERMs start, otherwise you are asking clomiphene or tamoxifen to restart an axis that hCG is still holding down.
Why is there no mg figure on my vial?+
Urinary hCG is standardised by bioassay, not by mass, so the label states IU of bioactivity. The powder in the vial is mostly mannitol or lactose, and specific activity varies by preparation, so any mg-per-vial number you see quoted for u-hCG is guesswork. Dose in IU and ignore mg.
References
- 1.Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression — The Journal of Clinical Endocrinology and Metabolism (2005) PMID 15713727
- 2.Maintenance of spermatogenesis in hypogonadotropic hypogonadal men with human chorionic gonadotropin alone — European Journal of Endocrinology (2002) PMID 12444893
- 3.Pulsatile GnRH or human chorionic gonadotropin/human menopausal gonadotropin as effective treatment for men with hypogonadotropic hypogonadism: a review of 42 cases — European Journal of Endocrinology (1998) PMID 9758439
- 4.PREGNYL (chorionic gonadotropin for injection, USP) US prescribing information — FDA prescribing information (2023)
More hpta & fertility
Gonadorelin
Native GnRH decapeptide, now the usual compounded stand-in for hCG on TRT.
200 mcg · 1-2x daily
hMG
Urine-derived FSH plus LH activity, added to hCG when sperm counts will not recover.
75 IU · 3x per week
Kisspeptin-10
Upstream GnRH trigger — the switch that makes the hypothalamus fire and the pituitary release LH.
50 mcg · 3x weekly on non-consecutive days
Triptorelin
Long-acting GnRH agonist taken as one microdose to fire off a large LH and FSH surge.
100 mcg · Single one-off dose