hCG
A long-acting LH mimetic that directly stimulates the testes to make testosterone and preserve fertility, and triggers ovulation in fertility medicine.
Human chorionic gonadotropin (hCG) is a placental glycoprotein hormone that binds the LH/CG receptor and behaves as a long-acting analogue of luteinizing hormone. In men it stimulates testicular Leydig cells to produce testosterone and helps preserve testicular size and spermatogenesis, most commonly as an off-label adjunct to testosterone replacement therapy; in women a large single dose is the standard ovulation trigger in IVF and timed-intercourse cycles. It is an FDA-approved prescription biologic for female fertility, male hypogonadotropic hypogonadism, and prepubertal cryptorchidism, but has no legitimate role in weight loss despite the debunked 'hCG diet.'
Class
Glycoprotein hormone (237-amino-acid heterodimer; long-acting LH analogue)
Half-life
~24-36 hours
Routes
Subcutaneous, Intramuscular
Category
Hormone & Reproductive
Researched benefits
What it's studied for
Direct testicular testosterone stimulation
hCG binds LH/CG receptors on Leydig cells and drives cAMP/PKA-mediated steroidogenesis, producing detectable testosterone elevation within hours that peaks 48-72 hours post-injection. This is FDA-approved for male hypogonadotropic hypogonadism, where it bypasses absent or suppressed endogenous LH.
Testicular size and function preservation on TRT
Because exogenous testosterone suppresses LH and causes testicular atrophy, low-dose hCG (typically 500 IU 2x weekly) supplies the missing downstream signal to keep the testes producing intratesticular testosterone. This has become the standard co-prescription for men on TRT who want to maintain testicular volume and fertility potential.
Fertility restoration and spermatogenesis support
hCG-driven Leydig cell testosterone maintains the high intratesticular testosterone needed by Sertoli cells for spermatogenesis. Combined with FSH (or hMG), it is used to restore sperm production after TRT or anabolic suppression, with reported success of sperm in ejaculate in roughly 60-80% of men within 6-12 months.
Ovulation trigger in female fertility treatment
A large single dose (5,000-10,000 IU) substitutes for the endogenous LH surge, triggering final oocyte maturation and ovulation within 34-42 hours. This is the standard 'trigger shot' in IVF and timed-intercourse protocols, an on-label use since the 1930s.
Cryptorchidism (undescended testicles)
An FDA-approved pediatric indication, typically used in boys about 4-9 years old, where hCG stimulation can promote testicular descent.
Luteal phase and corpus luteum support
Lower-dose hCG after ovulation sustains the corpus luteum and progesterone production, supporting establishment of early pregnancy in assisted reproduction contexts.
Mechanism
How it works
hCG signals primarily through the LH/CG receptor (LHCGR), a Gs-coupled GPCR expressed densely on Leydig cells of the testis, theca and granulosa cells of the ovary, and the corpus luteum. Receptor binding activates adenylyl cyclase, raising intracellular cAMP and activating protein kinase A, which upregulates steroidogenic enzymes (StAR, CYP17A1, CYP11A1, 3-beta-HSD) and drives cholesterol transport into mitochondria for steroid synthesis. The net effect is rapid production of testosterone in men and estrogen/progesterone in women; at higher doses a secondary phospholipase C / calcium pathway is also engaged.
The alpha subunit of hCG is identical to that of LH, FSH, and TSH, and its beta subunit is highly homologous to LH's, so hCG functions as an LH mimetic at the receptor. The defining pharmacological difference is half-life: LH is cleared in 20-30 minutes and secreted in pulses, whereas hCG's heavily glycosylated beta subunit with its C-terminal peptide extension resists clearance and gives a 24-36 hour half-life. A single injection can therefore maintain biologically meaningful LHCGR activation for roughly 3-7 days, which is precisely why hCG is therapeutically useful where short-acting recombinant LH is not.
In men, the primary action is Leydig cell stimulation to produce testosterone and, importantly, local intratesticular estradiol via testicular aromatase. This direct trophic signal preserves testicular size and supports (though does not fully restore) spermatogenesis, because full sperm production also requires FSH. Critically, hCG substitutes for LH rather than restoring endogenous LH: it does not act on the hypothalamus or pituitary (unlike kisspeptin or gonadorelin) and does not restart suppressed endogenous LH — which is exactly what makes it the tool of choice when the HPG axis is deliberately suppressed by exogenous testosterone.
Two dose-related caveats shape clinical use. First, hCG-stimulated testicular aromatization tends to raise estradiol more than an equivalent dose of exogenous testosterone, making estrogen monitoring and occasional aromatase-inhibitor management relevant. Second, continuous high-dose hCG can downregulate LHCGR expression and, with prolonged use, provoke anti-hCG antibodies (slightly more with urinary-derived than recombinant product) — which is why moderate, divided, 2-3x weekly dosing with periodic breaks is generally preferred over prolonged high-dose exposure.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Reconstitution
hCG ships as a lyophilized powder reconstituted with bacteriostatic water. The standard men's dilution is a 5,000 IU vial + 5 mL BAC water = 1,000 IU/mL, where on a U-100 insulin syringe 1 unit = 10 IU, 50 units (0.5 mL) = 500 IU, and 100 units (1 mL) = 1,000 IU. Other options: 5,000 IU + 2 mL = 2,500 IU/mL (1 unit = 25 IU) for higher doses in smaller volume; 10,000 IU + 10 mL = 1,000 IU/mL; 10,000 IU + 5 mL = 2,000 IU/mL; 5,000 IU + 10 mL = 500 IU/mL. Dribble the water slowly down the vial wall rather than onto the pellet, swirl gently (never shake) until clear and colorless, then refrigerate. Lyophilized vials are stable 24+ months refrigerated; reconstituted solution is stable ~30 days at 2-8C, must not be frozen, and should be protected from light.
Beginner - TRT fertility/size preservation
- Dose
- 500 IU
- Frequency
- 2x weekly
- Timing
- Typically on or the day before TRT injection days (e.g. Mon/Thu)
- Duration
- Ongoing co-administration throughout TRT
- Route
- Subcutaneous
Standard-of-care add-on to maintain testicular size, intratesticular testosterone, and fertility potential. Start at the low end and titrate. Monitor testosterone, estradiol, hematocrit, and PSA every 3-6 months.
Intermediate - Secondary hypogonadism (no fertility goal)
- Dose
- 1,000-2,000 IU
- Frequency
- 2-3x weekly
- Timing
- Divided doses across the week for smoother testosterone curves
- Duration
- Continue indefinitely if desired; cycle with breaks if preferred
- Route
- Subcutaneous
Titrate toward ~600-800 ng/dL mid-week total testosterone. Add anastrozole 0.5 mg 1-2x weekly only if estradiol rises above ~60 pg/mL with symptoms; avoid crushing estradiol below ~20 pg/mL.
Intermediate - Post-cycle recovery
- Dose
- 1,500-2,000 IU tapering to 500-1,000 IU
- Frequency
- 2-3x weekly
- Timing
- Weeks 1-4 at higher dose, weeks 5-8 taper, discontinue by weeks 9-12
- Duration
- 8-12 weeks
- Route
- Subcutaneous
Combine with a SERM (enclomiphene 12.5-25 mg daily, clomiphene 25-50 mg daily, or tamoxifen 20-40 mg daily). hCG restores Leydig cell output first; SERM supports axis recovery. Continue SERM 2-4 weeks after hCG stops; check T/LH/FSH/E2/prolactin/SHBG at weeks 12-16.
Advanced - Fertility restoration after TRT
- Dose
- 2,000-3,000 IU hCG + 75-225 IU FSH
- Frequency
- 3x weekly (each agent)
- Timing
- Requires stopping all exogenous testosterone first
- Duration
- 3-12 months (one spermatogenesis cycle is ~74 days plus transit)
- Route
- Subcutaneous
Add FSH (hMG or recombinant FSH); clomiphene/enclomiphene optional. Semen analysis every 3 months. Roughly 60-80% achieve sperm in ejaculate within 6-12 months and 40-70% achieve fertility. Best done with a reproductive urologist/endocrinologist.
Advanced - hCG monotherapy for chronic secondary hypogonadism
- Dose
- 1,500-2,500 IU (up to 3,000 IU)
- Frequency
- 2-3x weekly
- Timing
- Divided doses; consistent day-of-week for labs
- Duration
- Long-term; some cycle 8-12 weeks on, 2-4 weeks off
- Route
- Subcutaneous
Alternative to TRT for men with intact Leydig cells prioritizing fertility and testicular size. Does not work for primary hypogonadism (damaged/absent Leydig cells). Quarterly labs the first year, then semi-annual; manage estradiol as needed.
Clinical - Ovulation trigger (female, specialist-supervised)
- Dose
- 5,000-10,000 IU
- Frequency
- Single dose per cycle
- Timing
- At peak follicular maturation; ovulation follows in 34-42 hours
- Duration
- One cycle
- Route
- Intramuscular or subcutaneous
The standard IVF/timed-intercourse trigger shot administered under reproductive endocrinology supervision with ultrasound monitoring. Lower-dose hCG may follow for luteal phase support.
- Split dosing (2-3x weekly) is preferred over a single large weekly dose because a single 2,000 IU dose produces a higher estradiol peak than 2 x 1,000 IU.
- Doses above 3,000 IU per injection rarely add benefit for men's use and disproportionately increase estradiol-related side effects and receptor desensitization risk.
- SC injection with a 29-31G x 5/16 inch insulin syringe is simpler and less painful than IM and equally effective; rotate abdomen, flank, and thigh sites.
- Draw labs after 4-6 weeks of stable dosing for meaningful assessment; testicular size restoration/maintenance takes about 4-8 weeks.
- Pharmaceutical-grade product (Pregnyl, Novarel, Ovidrel) eliminates compounding and grey-market variability, where actual IU content can differ 20-50% from label; for ongoing protocols the quality is worth the cost.
- Do not use hCG for weight loss - controlled trials since the 1970s show no effect beyond the accompanying calorie restriction.
Evidence
Research & clinical studies (8)
FTO regulates testosterone secretion in Leydig cells: insights into the role of m6A modifications and the therapeutic potential of hCG
In 39 men with obstructive azoospermia and Leydig cell cultures, FTO expression correlated positively with testosterone; FTO knockdown reduced testosterone and increased apoptosis, while hCG treatment restored testosterone by 18-37%.
Peripheral Precocious Puberty in a Girl with hCG-Secreting Suprasellar Germ Cell Tumor: Authors' Reply
An hCG-secreting suprasellar germ cell tumor caused peripheral precocious puberty, illustrating the clinical link between hCG-producing tumors and early pubertal development in children.
PMID 42217079Epidemiological study of Ectopic Pregnancy at Sulaimani Maternity Teaching Hospital, Iraq: A cross-sectional study
Serum beta-hCG combined with transvaginal ultrasonography confirmed ectopic pregnancy in a cross-sectional study of 393 women, identifying 79 cases (20.1%), most of them tubal.
PMID 42216416Unexpected elevation of beta-hCG in EGFR-mutant lung adenocarcinoma: a case study and implications for clinical practice
Reports the first documented pulmonary adenocarcinoma presenting with both markedly elevated serum beta-hCG and an EGFR mutation, an atypical tumor-marker profile clinicians may encounter.
PMID 42215993Safety evaluation of a novel progesterone vaginal ring (PVR) for luteal phase support: SARA trial
A reformulated progesterone vaginal ring for luteal phase support showed comparable safety, a 7.4% spontaneous abortion rate within thresholds, and a 43.2% clinical pregnancy rate in fresh embryo transfer.
PMID 42213348Inducing physiological polarity and performing gene editing using CRISPR-Cas9 in human trophoblast organoids
Describes protocols for generating polarized, gene-edited human trophoblast organoids, the hCG-producing tissue used to model early placental biology.
PMID 42373862hCG preserves spermatogenesis in men undergoing testosterone replacement therapy (Hsieh et al.)
Low-dose hCG co-administered with TRT maintained intratesticular testosterone and preserved semen parameters, supporting hCG's role in fertility preservation during androgen therapy.
Systematic review of hCG for weight loss (Lijesen et al., Cochrane-style review)
Pooled controlled trials found no evidence that hCG produces weight loss, redistributes fat, or reduces hunger beyond the effect of the accompanying calorie-restricted diet.
Combinations
Stacking & blends
TRT + hCG (testicular preservation)
Maintain testicular size, intratesticular testosterone, and fertility during testosterone replacement
Exogenous testosterone suppresses LH and shrinks the testes; hCG supplies the missing downstream LH signal so the testes keep functioning. Anastrozole is added only if hCG-driven aromatization pushes estradiol too high.
hCG + FSH (fertility restoration)
Restore spermatogenesis after TRT or anabolic suppression
hCG restores Leydig cell testosterone but full spermatogenesis also needs FSH; the pair reconstitutes both signals, with reported sperm recovery in 60-80% of men over 6-12 months.
hCG + SERM (post-cycle recovery)
Recover the HPG axis after an anabolic steroid cycle
hCG rapidly restores testicular output while the SERM blocks estrogen negative feedback to help revive endogenous LH/FSH, a more complete recovery than either alone.
Sequential axis restoration
Rescue failed or complex post-cycle recovery
Layers direct gonadal stimulation (hCG) with pituitary (gonadorelin) and hypothalamic (kisspeptin) signals plus FSH and a SERM to address each level of a suppressed reproductive axis; used under specialist supervision.
Safety
Side effects & considerations
Commonly reported effects
Contraindications & cautions
- Hormone-dependent cancers (prostate cancer, estrogen-dependent breast cancer)
- Precocious puberty (pediatric)
- Known hypersensitivity to hCG preparations
- Active/uncontrolled thromboembolic disease
- Gonadotropin-secreting pituitary tumors
- Active hyperthyroidism
- Significant polycythemia (hematocrit >54)
- Ovarian hyperstimulation risk factors in women (PCOS, high AMH, prior OHSS)
- Pregnancy (for non-obstetric use)
hCG tends to raise estradiol more than equivalent testosterone because it activates testicular aromatase, so estradiol should be monitored (target ~30-50 pg/mL, not zero) and managed with low-dose anastrozole only if elevated with symptoms. In female fertility use, label-level serious risks include ovarian hyperstimulation syndrome, ovarian cyst rupture, multiple gestation, and thromboembolic events. Baseline and follow-up monitoring for men includes total/free testosterone, sensitive estradiol, SHBG, LH, FSH, CBC/hematocrit, and PSA. hCG causes positive pregnancy tests for days to weeks after injection and does not cause physical dependence.
FAQ
hCG — common questions
Why do men on TRT add hCG?
Exogenous testosterone shuts down the brain's LH signal, so the testes stop making their own testosterone and shrink. hCG mimics LH directly at the testicular receptor, so co-administering low-dose hCG (commonly 500 IU 2x weekly) preserves testicular size, maintains some endogenous testosterone, and protects fertility. It has become a standard co-prescription for men on TRT.
Does hCG cause gynecomastia?
It can, because hCG specifically activates testicular aromatase and tends to raise estradiol more than an equivalent testosterone dose. Keeping doses moderate, splitting them 2-3x weekly, monitoring estradiol, and adding low-dose anastrozole only if estradiol runs high with symptoms usually manages it. Watch for early nipple sensitivity or puffiness under the nipple, and avoid crushing estradiol to zero.
How is hCG different from gonadorelin or kisspeptin-10?
They act at different points in the reproductive axis. Kisspeptin-10 acts at the hypothalamus to drive GnRH, gonadorelin (synthetic GnRH) acts at the pituitary to drive LH/FSH, and hCG acts directly at the gonads, substituting for LH at the Leydig cell receptor. On TRT the upstream axis is intentionally suppressed, so only direct gonadal stimulation with hCG is effective.
Can hCG help with weight loss?
No. The hCG diet has been thoroughly debunked - rigorous trials show hCG injections plus a 500-calorie diet produce the same weight loss as placebo injections plus the same diet, meaning all the loss comes from calorie restriction. hCG has no effect on appetite, metabolism, or fat distribution, and homeopathic 'hCG drops' contain no meaningful hCG. The FDA has warned against hCG for weight loss since 2011.
Can I restore fertility after years on TRT using hCG?
Usually yes, but it takes time and typically requires adding FSH. A common approach is to stop TRT and run hCG 2,000-3,000 IU 3x weekly plus FSH 75-150 IU 3x weekly for 3-12 months with semen analysis every 3 months. Roughly 60-80% of men get sperm back in the ejaculate within 6-12 months and 40-70% achieve fertility, with better outcomes under a reproductive urologist or endocrinologist.
Is hCG FDA approved?
Yes. It is an approved prescription drug (Pregnyl, Novarel, recombinant Ovidrel) for female fertility induction, male hypogonadotropic hypogonadism, and prepubertal cryptorchidism. TRT-adjunct and post-cycle uses are off-label but common. The FDA does not approve hCG for weight loss and banned OTC homeopathic hCG in December 2011.
What doses of hCG are safe long-term?
For TRT fertility preservation, 500-1,000 IU 2-3x weekly has a good long-term track record; for hypogonadism monotherapy, 1,000-2,000 IU 2-3x weekly is well tolerated. Higher doses (2,500-3,000 IU) are usually reserved for shorter-term fertility restoration, and doses above ~3,000 IU per injection add little benefit while increasing estradiol and desensitization risk. Regular labs and clinical monitoring support safe long-term use.
How do I know if my compounded hCG is good quality?
Look for a reputable licensed compounding pharmacy, a clear label with concentration, compounding date, beyond-use date and lot number, a clean white lyophilized cake, and a clear colorless reconstituted solution. Biological verification helps: a correct dose should produce a measurable testosterone response within 48-72 hours. Pharmaceutical brands (Pregnyl, Novarel, Ovidrel) eliminate compounding variability entirely.
