HCG
Also known as: Human Chorionic Gonadotropin, Pregnyl, Novarel, Ovidrel
Human Chorionic Gonadotropin | LH Receptor Agonist
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.
Key benefits
- Maintains testicular function during TRT
- Preserves fertility and prevents testicular atrophy
- Stimulates endogenous testosterone production
- Induces ovulation in women
- FDA-approved for multiple indications
- Well-established safety profile
Mechanism of action
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.
Molecular data
- Type
- Heterodimeric glycoprotein
- Half-life
- 24-36 hours
Indications
What the research community uses this compound for, with self-reported effectiveness.
Male Fertility
TRT Adjunct
Most effectiveMaintains intratesticular testosterone at baseline during testosterone therapy, preventing atrophy and preserving fertility.
Hypogonadotropic Hypogonadism
Most effectiveFDA-approved for secondary hypogonadism; combined with FSH for spermatogenesis induction.
Post-Cycle Therapy
EffectiveRestores testicular function after anabolic steroid cycles.
Female Fertility
Ovulation Induction
Most effectiveFDA-approved trigger for follicular maturation; 15-25% pregnancy rate per cycle.
Pediatric
Cryptorchidism
ModerateFDA-approved for prepubertal undescended testes not due to anatomical obstruction; ~25% success rate.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Injectable
Subcutaneous or intramuscular injection. Administer 2-3 times weekly, evenly spaced. For TRT, many inject HCG on days between testosterone injections.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| TRT Adjunct (Low) | 250-500 IU | Every other day | SubQ/IM |
| TRT Adjunct (Standard) | 500-1000 IU | Twice weekly | SubQ/IM |
| HCG Monotherapy | 1500-2000 IU | 2-3x weekly | IM |
| Fertility (with FSH) | 1500-2000 IU | 2-3x weekly | IM |
| Cryptorchidism (Pediatric) | 1000-5000 IU | 2-3x weekly for 3-4 weeks | IM |
| Ovulation Trigger (Female) | 5000-10,000 IU | Single dose | IM/SubQ |
| PCT Protocol | 1000-1500 IU | Every other day for 2-3 weeks | SubQ/IM |
Preparation
You will need
- HCG lyophilized powder vial (typically 5000 or 10,000 IU)
- Bacteriostatic water or sodium chloride diluent (provided)
- Insulin syringes (29-31 gauge for SubQ)
- Alcohol prep pads
Steps
- Remove vial and diluent from packaging
- Clean rubber stoppers with alcohol swabs
- Draw diluent into syringe (typically 1-2mL provided)
- Slowly inject diluent into HCG vial, aiming at vial wall
- Gently swirl to dissolve - do not shake vigorously
- Allow to sit until completely dissolved and clear
- Calculate concentration (e.g., 5000 IU in 2mL = 2500 IU/mL)
- Label with reconstitution date and concentration
- Store reconstituted HCG at 2-8°C
- Use within 30-60 days
Work out the water volume and syringe units in the reconstitution calculator →
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Clomiphene (Clomid)
MonitorUse sequentially; both affect HPG axis.
GnRH Analogs
MonitorMonitor combination effects on gonadotropin axis.
Thyroid Hormones
MonitorHCG has weak TSH-like activity; monitor thyroid function.
Testosterone
SynergisticCommonly combined in TRT to maintain testicular function and preserve fertility.
Aromatase Inhibitors
CompatibleCommonly combined; HCG increases intratesticular aromatase activity.
FSH (Follitropin)
SynergisticSynergistic for fertility; 70-90% spermatogenesis induction rate.
Kisspeptin
CompatibleComplementary mechanisms for HPG axis stimulation.
Metformin
CompatibleProtective combination for metabolic health.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Day 1-3
Cellular-level action begins; no immediate noticeable effects
- Week 1-2
Testosterone increase detectable on labs; possible mood/energy improvement
- Week 2-4
Testicular fullness/size improvement noticeable; improved well-being
- Week 4-8
Stable testosterone levels; fertility parameters beginning to improve
- Month 2-3
Sperm count improvements if used for fertility; sustained testicular function
- Long-term
Maintained testicular size and function with ongoing use
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- 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
Stop signs — stop and seek advice
- 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
Contraindications
- Hormone-sensitive cancers (prostate, breast)
- Pregnancy (except as prescribed)
- Precocious puberty risk in children
Monitoring
- Monitor estrogen levels - may need aromatase inhibitor
- Regular testosterone and fertility panel
- Watch for gynecomastia signs
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- 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)
Warning signs
- Generic/compounding pharmacy products - quality varies
- Ensure compounding pharmacy is accredited
Stop signs — don't use
- Cloudiness, discoloration, or floating particles indicates degradation
- Compromised vial seal or expired product
Recent research
Newer papers and trial readouts on file for this compound, with source and date.
2024 · Fertility and Sterility
Optimal Restoration of Spermatogenesis after Testosterone Therapy Using Human Chorionic Gonadotropin and Follicle-Stimulating Hormone
In 77 men with testosterone-use-induced infertility, 74% demonstrated improvements in sperm concentrations with HCG/FSH therapy. Concurrent testosterone does not impede recovery.
2025 · Nature Reviews Urology
Preserving Spermatogenesis in Testosterone Deficiency: Innovations in Replacement and Stimulatory Therapies
Comprehensive review of evolving treatment modalities. HCG maintains sperm production even with full gonadotropin suppression from TRT. AUA guidelines recommend HCG for fertility-preserving hypogonadism treatment.
References
Primary literature and clinical-trial data informing this entry.
Low-Dose Human Chorionic Gonadotropin Maintains Intratesticular Testosterone in Normal Men with Testosterone-Induced Gonadotropin Suppression
Coviello 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 Chorionic Gonadotropin Monotherapy for the Treatment of Hypogonadal Symptoms in Men with Total Testosterone >300 ng/dL
Alder 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.
Fertility Induction in Hypogonadotropic Hypogonadal Men
Rastrelli 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%).
The Effectiveness of hCG and LHRH in Boys with Cryptorchidism: A Meta-Analysis of Randomized Controlled Trials
Defined 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.
Efficacy and Safety of Human Chorionic Gonadotropin for Treatment of Cryptorchidism: A Meta-Analysis of Randomised Controlled Trials
Defined 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.
Last updated . How this page was sourced is described in the methodology.
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