HCG
Human Chorionic Gonadotropin · LH Receptor Agonist
HCG is a glycoprotein hormone naturally produced by the placenta during pregnancy that binds LH receptors to stimulate testosterone and estrogen biosynthesis. FDA-approved for cryptorchidism, hypogonadotropic hypogonadism, and ovulation induction.
Overview
HCG is a glycoprotein hormone naturally produced by the placenta during pregnancy that binds LH receptors to stimulate testosterone and estrogen biosynthesis. FDA-approved for cryptorchidism, hypogonadotropic hypogonadism, and ovulation induction.
Binds to LH receptors on Leydig cells in testes, stimulating testosterone production with a half-life of 24-36 hours, peak levels 6-12 hours post-injection, and 40-50% bioavailability via SubQ or IM routes.
Research indications
What the compound has been studied for, grouped by body system. Effect size is the reported magnitude where it was measured — not a recommendation.
Maintains intratesticular testosterone at baseline during testosterone therapy, preventing atrophy and preserving fertility.
FDA-approved for secondary hypogonadism; combined with FSH for spermatogenesis induction.
Restores testicular function after anabolic steroid cycles.
FDA-approved trigger for follicular maturation; 15-25% pregnancy rate per cycle.
FDA-approved for prepubertal undescended testes not due to anatomical obstruction; ~25% success rate.
A large effect in a weak study and a small effect in a strong one are different things. Effect size is never evidence of use in people.
- Class
- Heterodimeric glycoprotein
- Chain length
- 237 residues
- Molecular weight
- 36700 Da
- Half-life
- ~30 h
- Typical dose
- 250-1500 IU (lower for TRT adjunct, higher for fertility)
- Frequency
- 2-3 times weekly, or every other day for lower doses
- Cycle length
- Ongoing with TRT or 3-6 months for fertility protocols
- Storage
- Lyophilized: Room temperature. Reconstituted: 2-8°C, use within 30-60 days
Molecular data
- Type
- Heterodimeric glycoprotein
- Molecular weight
- 36700 Da
- Chain length
- 237 residues
- Half-life
- 1800 min
Dosing reference
Doses reported in the literature and by suppliers. These are a record of what has been used in research — reference, never instruction.
| Context | Route | Amount | Frequency |
|---|---|---|---|
| TRT Adjunct (Low) | SubQ/IM | 250-500 IU | Every other day |
| TRT Adjunct (Standard) | SubQ/IM | 500-1000 IU | Twice weekly |
| HCG Monotherapy | IM | 1500-2000 IU | 2-3x weekly |
| Fertility (with FSH) | IM | 1500-2000 IU | 2-3x weekly |
| Cryptorchidism (Pediatric) | IM | 1000-5000 IU | 2-3x weekly for 3-4 weeks |
| Ovulation Trigger (Female) | IM/SubQ | 5000-10,000 IU | Single dose |
| PCT Protocol | SubQ/IM | 1000-1500 IU | Every other day for 2-3 weeks |
Interactions
Commonly combined in TRT to maintain testicular function and preserve fertility.
Use sequentially; both affect HPG axis.
Commonly combined; HCG increases intratesticular aromatase activity.
Monitor combination effects on gonadotropin axis.
Synergistic for fertility; 70-90% spermatogenesis induction rate.
Complementary mechanisms for HPG axis stimulation.
HCG has weak TSH-like activity; monitor thyroid function.
Protective combination for metabolic health.
Quality checklist
- ✓White to off-white lyophilized powder or cake in sealed vial
- ✓Completely clear solution after reconstitution
- ✓Proper labeling: Pregnyl, Novarel (urinary), Ovidrel (recombinant)
- ✓Clear expiration and lot number
- ✓Cold chain compliance (recombinant requires refrigeration throughout)
- !Generic/compounding pharmacy products - quality varies
- !Ensure compounding pharmacy is accredited
- ×Cloudiness, discoloration, or floating particles indicates degradation
- ×Compromised vial seal or expired product
What to expect
Safety
- Gynecomastia (breast tenderness/swelling) due to increased estrogen
- Headaches, irritability, and mood swings (especially initially)
- Fluid retention and edema
- Potential antibody formation with long-term use
- Signs of gynecomastia (breast tenderness, swelling, nipple sensitivity)
- Severe or persistent headaches
- Signs of blood clots (leg swelling/pain, shortness of breath, chest pain)
- Allergic reactions (rash, hives, difficulty breathing, facial swelling)
- Severe abdominal pain or bloating in women (possible OHSS)
- Testicular pain or swelling beyond normal
- Significant mood changes (depression, aggression, severe irritability)
- Vision changes
- Hormone-sensitive cancers (prostate, breast)
- Pregnancy (except as prescribed)
- Precocious puberty risk in children
FAQ
How much HCG is needed to maintain fertility during testosterone replacement therapy?
A landmark clinical study found 250 IU of HCG every other day maintained intratesticular testosterone within 7% of baseline during testosterone therapy, preserving fertility. This low dose is far less than other protocols suggesting HCG is remarkably potent—even minimal doses maintain testicular function when properly timed.
Why does HCG cause gynecomastia if it just stimulates testosterone?
HCG stimulates testosterone production, but testes also express aromatase enzyme that converts testosterone to estrogen. The increased testosterone availability combined with enhanced intratesticular aromatase activity results in elevated estrogen, causing breast tenderness and gynecomastia. Aromatase inhibitors help prevent this side effect.
Can antibodies to HCG develop with long-term use and reduce effectiveness?
Potential antibody formation to HCG with extended use is a theoretical concern, though clinical significance remains unclear. Some users report diminishing HCG effectiveness after months of continuous use. Cycling HCG with breaks or rotation to GnRH analogs may prevent tolerance development.
What's the success rate of HCG for treating cryptorchidism (undescended testes)?
Meta-analysis of HCG in cryptorchidism shows approximately 24% success rate—modest but clinically relevant for select cases. Success is higher for bilateral versus unilateral cryptorchidism. This low success rate led to surgery becoming the standard treatment for most cases, though HCG remains an initial option.
References
- 1Low-Dose Human Chorionic Gonadotropin Maintains Intratesticular Testosterone in Normal Men with Testosterone-Induced Gonadotropin SuppressionCoviello AD, Matsumoto AM, Bremner WJ, et al. · Journal of Clinical Endocrinology & Metabolism · 2005
29 men randomized to testosterone enanthate plus 125, 250, or 500 IU HCG every other day. 250 IU maintained intratesticular testosterone within 7% of baseline, preserving fertility potential during TRT.
human-rctPubMed 15713727 ↗ - 2The Effectiveness of hCG and LHRH in Boys with Cryptorchidism: A Meta-Analysis of Randomized Controlled TrialsDefined a, et al. · Asian Journal of Andrology · 2016
Meta-analysis of 13 studies with 872 boys and 1,174 undescended testes. Overall HCG success rate of 24%. Significant effect on bilateral but not unilateral cryptorchidism.
meta-analysisPubMed 27050251 ↗ - 3Fertility Induction in Hypogonadotropic Hypogonadal MenRastrelli G, Corona G, Mannucci E, Maggi M · Endocrine Reviews · 2018
Combined HCG and FSH therapy induces spermatogenesis in 86% (95% CI 82-91%) of men with hypogonadotropic hypogonadism. HCG alone achieves 40% (95% CI 25-56%).
reviewPubMed 30194850 ↗ - 4Efficacy and Safety of Human Chorionic Gonadotropin for Treatment of Cryptorchidism: A Meta-Analysis of Randomised Controlled TrialsDefined a, et al. · Journal of Pediatric Surgery · 2018
Confirmed ~25% success rate for HCG in cryptorchidism treatment. All side effects were transitory and not severe.
meta-analysisPubMed 29655188 ↗ - 5Human Chorionic Gonadotropin Monotherapy for the Treatment of Hypogonadal Symptoms in Men with Total Testosterone >300 ng/dLAlder NJ, Waguih WI, et al. · International Journal of Impotence Research · 2019
HCG monotherapy safe and efficacious for hypogonadal symptoms. Erectile dysfunction improved in 86% (19/22), libido in 80% (20/25). No thromboembolic events.
reviewPubMed 31408289 ↗