HCG Quick Start
Human chorionic gonadotropin is a ~37 kDa glycoprotein hormone produced by the placenta. It shares its alpha subunit with LH, FSH and TSH, and its beta subunit is close enough to luteinizing hormone that it binds and activates the LH/hCG receptor with a much longer half-life than LH itself. Unlike most compounds in this catalog it is an FDA-licensed biologic with decades of labeled use, so its reference schedules have a firm clinical basis. It is also the only item here supplied and dosed entirely in international units (IU).
This guide is an educational research reference. It does not diagnose, treat, or prescribe, and is not medical advice. Consult a licensed clinician before considering any compound.
HCG Dosing Protocol
HCG is dosed in international units, never milligrams. The reference schedules below come from the labeled indications of the licensed products (Pregnyl, Novarel) and from the adjunct-therapy literature; they are shown as research context, not personal dosing recommendations. The units column assumes the 10 mL reconstitution worked out in the next section (1,000 IU/mL).
Injection — Subcutaneous
| Band | Per dose | Units (U-100) | Frequency |
|---|---|---|---|
| Adjunct / low | 250 IU | 25 u | 2–3× weekly |
| Adjunct / standard | 500 IU | 50 u | 2–3× weekly |
| Labeled: hypogonadotropic hypogonadism | 1,000–2,000 IU | 100–200 u | 3× weekly |
| Labeled: ovulation trigger | 5,000–10,000 IU | Single dose | Once |
Cycle guidelines
| Approach | Duration | Review point | Best for |
|---|---|---|---|
| Short | 4–6 weeks | Week 4 | General research planning; testosterone/estradiol check |
| Extended | 3–6 months | Monthly | Mirrors labeled hypogonadism regimens |
| Single dose | One injection | 36 h | Ovulation-trigger literature |
The literature consistently pairs any multi-week hCG schedule with periodic testosterone and estradiol measurement; aromatisation of the induced testosterone rise is the usual reason a dose is revised downward.
HCG Reconstitution Guide
HCG ships as a lyophilized powder labeled in IU. Because the vial is large (10,000 IU) and the common bands are small (250–500 IU), a 10 mL reconstitution gives a comfortable 25–50 unit draw and a round 1,000 IU/mL figure. A 10 mL fill does not fit a 3 mL vial — check the vial size on the label; many 10,000 IU vials are 10 mL. If yours is smaller, use the 5 mL row.
Injection
| BAC | Conc. | 500 IU |
|---|---|---|
| 10 mL | 1,000 IU/mL | 0.50 mL · 50 u |
| 5 mL | 2,000 IU/mL | 0.25 mL · 25 u |
| 2 mL | 5,000 IU/mL | 0.10 mL · 10 u |
Units are U-100 insulin-syringe units (100 u = 1.0 mL). At 2 mL the adjunct bands become very small draws; 5–10 mL is the practical range.
IU, not milligrams
HCG potency is defined by bioassay against an international standard, so the label reads in IU and there is no milligram figure to convert. The reconstitution calculator has an HCG preset that works in IU; the formula is per-unit IU = total IU ÷ (fill mL × 100).
Reconstitution steps
- Inspect the vial. Confirm the label, the 10,000 IU strength, and that the powder looks dry and intact.
- Wipe the stoppers. Use an alcohol swab on both the bacteriostatic water and peptide vial stoppers.
- Draw the chosen volume. 10 mL (or 5 mL for a smaller vial) into the vial — this is the number that sets every concentration figure above.
- Inject down the wall. Release the water slowly down the inside wall, not directly onto the powder.
- Swirl, do not shake. Roll gently until dissolved. Shaking foams and can damage the peptide.
- Verify clarity. Solution should be clear and colorless. Discard if cloudy or particulate. Some licensed products ship with their own diluent; bacteriostatic water is the research-standard alternative.
- Label and refrigerate. Note the date and volume added on the vial, then store at 2–8 °C. Do not freeze the reconstituted solution.
See the bacteriostatic water guide for diluent handling, or the reconstitution calculator to work any other volume.
How HCG Works
HCG binds the LH/hCG receptor, a G-protein-coupled receptor on testicular Leydig cells and ovarian theca and granulosa cells. In the male axis it drives testosterone synthesis directly at the gonad, bypassing the hypothalamus and pituitary; in the female axis a bolus mimics the mid-cycle LH surge and triggers final oocyte maturation and ovulation. Its extensive glycosylation gives it a circulating half-life of roughly 24–36 hours, far longer than native LH, which is why a two-to-three-times-weekly schedule maintains receptor stimulation.
LH-receptor agonism
Shares LH's receptor and downstream cAMP signalling; acts at the gonad, not the pituitary.
Leydig-cell steroidogenesis
Raises intratesticular and serum testosterone; the basis of its use in hypogonadotropic hypogonadism and as a TRT adjunct.
Ovulation trigger
A 5,000–10,000 IU bolus substitutes for the LH surge in assisted reproduction.
Long half-life
~24–36 h; supports intermittent rather than daily dosing.
Who Should Avoid HCG
An FDA-licensed biologic with defined contraindications in its labeling — these transfer directly to any research use.
Hormone-sensitive cancers
Contraindicated with prostate cancer or other androgen-dependent neoplasia; androgen stimulation is the mechanism.
Precocious puberty
Labeled contraindication; gonadal stimulation in a still-developing axis.
Pregnancy
Outside supervised ovulation-trigger protocols, hCG has no place in pregnancy.
Ovarian hyperstimulation risk
OHSS is the principal serious adverse event of trigger-dose use in stimulated cycles.
HCG Side Effects & Safety
Estradiol rise / gynecomastia
Induced testosterone aromatises; estradiol elevation and gynecomastia are the most common reasons a dose is reduced.
Fluid retention & headache
Reported in labeling; typically dose-related.
Injection-site reactions
Redness or discomfort at the site; rotate sites.
Ovarian hyperstimulation (OHSS)
A recognised serious event in ovulation-trigger use; not relevant to adjunct bands but included for completeness.
Weight-loss claims
The FDA has stated hCG has no demonstrated efficacy for weight loss; that use is not supported by evidence.
Timeline & What to Monitor
| Timeframe | Commonly tracked | Notes |
|---|---|---|
| Week 1–2 | Injection-site tolerance, fluid retention | Early gonadal-axis effects appear here. |
| Week 4–6 | Total testosterone, estradiol | The primary biochemical readout; estradiol drives most dose revisions. |
| Month 3–6 | Hematocrit, PSA (where relevant) | Longer-run androgen-exposure markers on extended schedules. |
HCG Evidence Context
Licensed indications
Approved for prepubertal cryptorchidism, hypogonadotropic hypogonadism in males, and ovulation induction in anovulatory infertility.
TRT adjunct literature
Low-dose hCG alongside exogenous testosterone is reported to preserve intratesticular testosterone and spermatogenesis.
Assisted reproduction
The standard ovulation trigger in IVF/IUI protocols for decades.
Weight loss
Repeatedly studied and repeatedly negative; the FDA position is that it is ineffective for that purpose.
Storage & Handling
| State | Storage | Notes |
|---|---|---|
| Lyophilized (powder) | 15–30 °C (room temperature) | Licensed products are labeled for room-temperature storage before reconstitution; refrigeration is acceptable. |
| Reconstituted (liquid) | 2–8 °C | Labeled products specify use within 30–60 days refrigerated; do not freeze. |
| Appearance | Clear, colorless | Discard cloudy or particulate solutions. |
HCG vs Other Gonadal-Axis Compounds
| Feature | HCG | Kisspeptin / GnRH analogs |
|---|---|---|
| Site of action | Gonad (LH receptor) | Hypothalamus / pituitary |
| Effect on pituitary LH | Suppresses via negative feedback | Stimulates (pulsatile) or suppresses (continuous) |
| Dosing unit | International units | Micrograms |
| Half-life | ~24–36 h | Minutes to hours |
Frequently Asked Questions
What is HCG?
Human chorionic gonadotropin, a placental glycoprotein hormone that acts as a long-acting LH analog. It is an FDA-licensed biologic with labeled uses in hypogonadism, cryptorchidism and ovulation induction.
Why is it dosed in IU instead of milligrams?
Its potency is defined by bioassay against an international standard, so the label reads in international units and there is no milligram equivalent to convert to.
How do I reconstitute a 10,000 IU vial?
Add 10 mL of bacteriostatic water for 1,000 IU/mL. On a U-100 syringe that makes 250 IU a 25-unit draw and 500 IU a 50-unit draw. Check that the vial is large enough for 10 mL; if not, use 5 mL for 2,000 IU/mL.
How many doses are in a vial?
Twenty at 500 IU, forty at 250 IU. A single ovulation-trigger dose can be the whole vial.
What should be monitored?
Total testosterone and estradiol are the primary markers; hematocrit and PSA on longer schedules. Estradiol elevation is the usual trigger for a dose reduction.
Does HCG work for weight loss?
No. Controlled trials have not shown any effect beyond the accompanying diet, and the FDA has stated it is not effective for weight loss.
Is this page medical advice?
No. It is an educational research reference and does not diagnose, treat, or prescribe. Consult a licensed clinician before considering any compound.
HCG Formats & Sourcing
HCG is supplied as a lyophilized powder in a single 10,000 IU vial. There is no pre-reconstituted pen or spray format. Batch-specific Certificates of Analysis are issued per lot.
| Format | Supplied as |
|---|---|
| Vial | 10,000 IU lyophilized powder |
Strengths are listed as sold; confirm against the product page and the batch COA before calculating anything.
Reference material for this protocol:
View HCG on Spyro Peptides →References
- U.S. FDA. Pregnyl (chorionic gonadotropin for injection, USP) prescribing information. Organon.
- U.S. FDA. Novarel (chorionic gonadotropin for injection, USP) prescribing information. Ferring.
- Hsieh TC, et al. Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy. J Urol (2013).
- Coviello AD, et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab (2005).
- Lijesen GK, et al. The effect of human chorionic gonadotropin (HCG) in the treatment of obesity by means of the Simeons therapy: a criteria-based meta-analysis. Br J Clin Pharmacol (1995).