HCG
The placental hormone of pregnancy, used as a prescription drug to trigger egg maturation in IVF and to replace LH in men whose pituitary makes too little. Its off-label use alongside testosterone rests on two small studies; its use for weight loss was tested and failed.
Human chorionic gonadotropin (hCG) acts, in its labels' words, virtually identically to pituitary LH: it drives the testes' Leydig cells to make testosterone and the ovary's corpus luteum to make progesterone. It has been a US prescription drug since the 1970s, and on March 23, 2020 FDA began regulating it as a biologic. The labels state it has not been shown to work for obesity.
What is it?
Human chorionic gonadotropin is made by the placenta; during a normal pregnancy it keeps the corpus luteum producing oestrogen and progesterone after the pituitary's LH falls away. As a medicine it does something simpler. Its labels describe its action as virtually identical to pituitary LH, with a small degree of FSH activity: it stimulates the Leydig cells of the testis to make androgens and the corpus luteum of the ovary to make progesterone. The US sells two kinds. Pregnyl, Novarel and a generic chorionic gonadotropin are dosed in USP units, and the Pregnyl and Novarel labels say they are purified from the urine of pregnant women; Ovidrel is recombinant hCG, a prefilled syringe of 250 µg. On March 23, 2020 every one of these approvals was deemed a biologics licence under the Biologics Price Competition and Innovation Act, the same transition FDA's list records for growth-hormone products.
In fertility clinics hCG is the trigger. Once ultrasound and oestradiol show that follicles are ready, a single dose, 5,000 to 10,000 units of urinary hCG or 250 µg of Ovidrel, replaces the mid-cycle LH surge; in the timing trial below, eggs were collected 35 to 36 hours later. The trials below refine that step rather than question it: delaying the trigger by one or two days in a 125-woman trial did not reduce eggs or live births, and swapping the last days of FSH-type stimulation for 200 units of hCG a day used about 40% less medication with similar pregnancy rates. The real trade-off is ovarian hyperstimulation syndrome. A Cochrane review of 17 trials found that triggering with a GnRH agonist instead cut the syndrome sharply, an odds ratio of 0.15, but in fresh cycles also cut live births, an odds ratio of 0.47, unless the luteal support that followed carried LH activity.
In men whose pituitary makes too little LH, hCG stands in for it. The label regimens run for months: 500 to 1,000 units three times a week at first, or 4,000 units three times a week for six to nine months. Sperm production usually needs FSH as well, which is why the studies here pair hCG with recombinant FSH or an FSH analogue: in seven men with adult-onset hypogonadotropic hypogonadism, hCG and FSH twice a week brought sperm back in five, and in 17 adolescent boys an FSH analogue followed by hCG grew the testes more than ninefold over 64 weeks. That study's authors note that testosterone or hCG alone virilises boys without growing the testes. Children are also given a single hCG injection as a test: a rise in testosterone shows working Leydig cells, which matters for a boy with an undescended testis.
The off-label use most readers come for is hCG alongside testosterone therapy. Injected testosterone switches off the body's own LH and, with it, the very high testosterone level inside the testis that is thought to be needed for sperm production. In the key experiment, 29 healthy men given 200 mg of testosterone enanthate a week lost 94% of their testicular testosterone in three weeks; 250 units of hCG every other day held it within 7% of baseline, and 500 units pushed it 26% above. A retrospective review of 26 men on testosterone plus 500 units every other day then found no fall in semen quality during follow-up (mean 6.2 months, some beyond a year), no case of azoospermia and nine pregnancies. Those two studies are the evidence the practice rests on: one measured hormones for three weeks, the other had no comparison group. No randomised trial has compared fertility on testosterone with and without hCG.
Two case reports describe bodybuilders whose testes stayed shut down after anabolic steroids and recovered on hCG, one on hCG alone and one on hCG with hMG; a case report cannot say how many men would have recovered without it. A 2019 case series gave hCG alone to 20 men with symptoms of low testosterone but levels above the usual 300 ng/dL threshold: testosterone rose about 50% and half felt better, with no placebo group. Men using hCG should know two practical points from the labels: hCG cross-reacts in laboratory LH assays, so the lab needs to be told, and the recorded side effects include water and sodium retention at high doses and, sporadically, breast enlargement.
hCG's most persistent off-label use has no support. The 'HCG diet' pairs the hormone, or products claiming to contain it, with about 500 calories a day. A 1995 meta-analysis scored 24 trials and found that of the 12 better-quality studies only one called hCG useful; it concluded that hCG does not cause weight loss, redistribute fat or reduce hunger. The Pregnyl and Novarel labels say the same in capital letters, and FDA advises consumers to avoid HCG weight-loss drops, pellets and sprays: hCG is not approved without a prescription for any purpose, and any weight lost comes from the calorie restriction, which FDA warns can cause gallstones, electrolyte imbalance and an irregular heartbeat.
hCG is also a laboratory marker. Germ-cell tumours can make it, and in a reference study of 795 healthy adults it was essentially undetectable in those under 45 with normal gonadal function; every higher value, in healthy people and in 732 testicular-cancer survivors, was explained by failing gonads, so the authors advise investigating a raised hCG in anyone whose LH and FSH are normal. The Novarel label records sporadic reports of testicular tumours in young men given hCG for infertility, without an established causal link.
Mechanism of Action
hCG binds the same receptor as luteinizing hormone. Everything it does as a drug follows from standing in for LH where LH is missing, suppressed or needs a timed surge.
Testosterone from the testis
hCG stimulates the Leydig cells to make androgens, so testosterone rises even when the pituitary sends no LH; in children a single dose tests whether those cells work at all.
Keeps testicular testosterone up on testosterone therapy
Injected testosterone suppressed LH to 5% and testicular testosterone by 94% in three weeks; 250 to 500 units every other day held the testicular level near or above baseline.
The ovulation trigger
In the menstrual cycle the mid-cycle LH surge triggers ovulation, and the labels state hCG can substitute for LH in this function, which is how a single injection completes egg maturation before IVF retrieval.
Corpus luteum support
hCG stimulates the corpus luteum to make progesterone, as it does in early pregnancy; which fits the Cochrane finding that pregnancy rates after a GnRH-agonist trigger fell only when the luteal support that followed lacked LH activity.
No effect on fat or appetite
The labels state hCG has no known effect on fat mobilisation, appetite or body fat distribution, and the diet trials agree.
Published Research
PubMed returns about 50,400 records for chorionic gonadotropin or hCG. That is the whole literature on the pregnancy hormone, including pregnancy tests, IVF and tumour markers, not a count of studies of hCG as a drug. Our evidence set holds 57 papers; 20 name hCG in their titles and have an abstract, and 15 are carded below: 12 studies in people, 2 reviews and 1 mouse study. The others concern prenatal screening, pregnancy complications and animal breeding, which use hCG as a measurement rather than a treatment.
Testosterone plus low-dose hCG: testicular testosterone, 29 men
Healthy men received testosterone enanthate 200 mg weekly with saline or 125, 250 or 500 IU hCG every other day for three weeks. Testosterone alone cut LH and FSH to 5% and 3% of baseline and testicular testosterone by 94% (1,234 to 72 nmol/L). With hCG it rose with dose: 25% below baseline at 125 IU, 7% below at 250 IU and 26% above at 500 IU. The study measured hormones, not sperm.
Testosterone plus hCG 500 IU: semen over a year, 26 men
A retrospective review of hypogonadal men on testosterone gel or weekly injections with 500 IU hCG intramuscularly every other day. Semen parameters did not change during follow-up (mean 6.2 months, some men beyond a year), no man became azoospermic, and 9 of the 26 contributed to a pregnancy. There was no group on testosterone alone for comparison.
hCG alone for symptoms, testosterone above 300 ng/dL, 20 men
A retrospective multi-centre case series of men with low libido, low energy or erectile dysfunction whose testosterone was above the 300 ng/dL treatment threshold. Mean testosterone rose 49.9%, from 362 to 519.8 ng/dL; median treatment was 8 months; half reported improvement and no adverse events were recorded. There was no placebo group.
Steroid-induced hypogonadism: one bodybuilder
A competitive bodybuilder developed profound hypogonadism after anabolic steroid use, and it returned when he stopped prescribed testosterone. Weekly hCG injections for three months restored testicular function, which stayed normal afterwards without treatment. A single case report.
Persistent steroid azoospermia: hCG with hMG, one man
A bodybuilder who had used seven anabolic steroids was still azoospermic a year after stopping. Twice-weekly 10,000 IU hCG with daily 75 IU hMG for three months returned his semen analysis to normal, and the couple conceived spontaneously seven months later. A single case report.
Adult-onset hypogonadotropic hypogonadism: hCG + FSH, 7 men
Seven men aged 34 to 45 with azoospermia or sexual dysfunction and no identifiable cause received 5,000 IU hCG and 150 IU recombinant FSH twice weekly. Spermatogenesis returned in five of the seven; one couple conceived naturally, and sperm from four men was frozen for later ICSI.
Adolescent boys: an FSH analogue, then hCG, 17 boys
Boys aged 14 to 17 with hypogonadotropic hypogonadism received corifollitropin alfa every two weeks for 12 weeks, then with twice-weekly hCG (500 to 5,000 IU, adjusted to hormone levels) for 52 weeks. Testicular volume rose 9.4-fold, 13.0 mL on average, with pubertal progression and a growth spurt; no boy developed antibodies. A single-group study without controls.
The hCG stimulation test in boys with micropenis, 6 children
A single 100 IU/kg injection tests whether a child's Leydig cells can make testosterone. In six children mean testosterone rose from 0.3 to 1.26 ng/mL; three had a normal rise, including one with an undescended testis, suggesting viable testicular tissue. Stretched penile length did not change significantly.
When to give the IVF trigger, 125 women (RCT)
Women on a GnRH-antagonist IVF protocol received hCG when three follicles reached 17 mm, or one or two days later. Oocyte numbers were the same (median 12 in each group), and live birth rates of 17.9%, 27.0% and 25.8% did not differ significantly. Delaying the trigger did not harm outcomes, which lets clinics avoid weekend retrievals.
Low-dose hCG in place of hMG late in stimulation, 122 women
In a GnRH-agonist long protocol, 60 women switched from hMG to 200 IU hCG a day once six follicles reached 12 mm, while 62 continued hMG to a 10,000 IU trigger. Clinical pregnancy rates were 40% and 35.5%, not significantly different, and the hCG group used far less gonadotropin (1,439 vs 2,524 IU).
Cochrane: GnRH-agonist vs hCG trigger, 17 RCTs
In fresh IVF cycles an agonist trigger in place of hCG cut ovarian hyperstimulation syndrome (OR 0.15; 8 trials, 989 women) but lowered live birth (OR 0.47; 5 trials, 532 women): a 31% chance with hCG becomes 12% to 24%. The pregnancy deficit applied only when luteal support lacked LH activity, and donor-recipient cycles showed no difference in live birth.
Recombinant hCG: liquid vs freeze-dried, bioequivalence
A phase I crossover in healthy adults gave single 250 µg doses of recombinant hCG as a liquid and as reconstituted powder. Peak levels were 125 and 129 mIU/mL, reached at a median 20 and 24 hours, and the formulations were bioequivalent within FDA's 0.8 to 1.25 range. Headache and nausea were the most frequent adverse events.
The hCG diet: a meta-analysis of 24 trials
Eight controlled and 16 uncontrolled trials of hCG with the Simeons very-low-calorie diet were scored for method; most were poor (16 to 73 of 100 points). Of the 12 better studies, all controlled, one found hCG a useful adjunct. The authors found no evidence that hCG causes weight loss, redistributes fat, reduces hunger or improves well-being.
hCG as a tumour marker: reference limits in 795 adults
In healthy adults under 45 with normal LH and FSH, hCG was barely detectable (97.5th percentiles 0.1 IU/L in men, 0.2 in women), so the authors proposed a common limit below 0.3 IU/L. Every higher value, among healthy people and 732 testicular-cancer survivors, was explained by reduced gonadal function, so a raised hCG with normal gonadal function should prompt investigation.
hCG vs GnRH-agonist trigger in mice: uterine blood-vessel signals
In a mouse model of assisted reproduction the two triggers shifted angiogenic factors differently: endometrial VEGF receptor mRNA was higher after the agonist trigger before implantation, while hCG raised serum VEGFA and soluble VEGFR1 and placental VEGFA at midgestation. What this means for human pregnancy has not been tested.
Dosing Data
Urinary hCG is dosed in USP units and recombinant Ovidrel in micrograms. The label regimens below are the approved ones; the two testosterone-therapy rows come from the small studies above and are not an approved use.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Side Effects & Contraindications
Reported Side Effects
From the Pregnyl and Novarel labels and the studies above.
Contraindications & Cautions
From the Pregnyl and Novarel labels; a clinician decides.
Legal Status
hCG is a prescription biologic in the US; the sport row below comes from the dataset.
Frequently Asked Questions
?Does hCG preserve fertility on testosterone therapy?
It keeps testicular testosterone near normal: in a three-week study, 250 to 500 units every other day held it at 93% to 126% of baseline while testosterone alone cut it by 94%. In one review of 26 men without a comparison group, semen quality held during follow-up (mean 6.2 months) and nine contributed to a pregnancy. No randomised trial has compared fertility on testosterone with and without hCG.
?Does the HCG diet work?
No. A meta-analysis of 24 trials found no evidence that hCG causes weight loss, moves fat or reduces hunger, and the Pregnyl and Novarel labels say so in capital letters. FDA advises consumers to avoid HCG weight-loss drops, pellets and sprays; any weight lost comes from the 500-calorie diet, which carries its own risks.
?Is hCG a peptide?
It is a glycoprotein hormone: two protein chains of 92 and 145 amino acids carrying sugar chains, so this site classes it as a protein rather than a short peptide. Since March 23, 2020 FDA has regulated it as a biologic, like growth-hormone products.
?What is the difference between Pregnyl, Novarel and Ovidrel?
Pregnyl and Novarel are hCG purified from the urine of pregnant women, dosed in USP units and injected into muscle; they carry labels for undescended testes, male hypogonadotropic hypogonadism and ovulation induction. Ovidrel is recombinant hCG in a 250 µg prefilled syringe, labelled for triggering final egg maturation in fertility treatment.
?How long does mixed hCG keep?
By the labels, reconstituted Pregnyl is stable for 60 days in the refrigerator and reconstituted Novarel should be refrigerated and used within 30 days. Neither may be frozen. These figures apply to those products and their supplied solvents.
?Why is compounded hCG hard to find?
Because hCG became a biologic on March 23, 2020. A 2023 survey found that only 5 of 75 FDA-registered 503B outsourcing facilities that answered still supplied it, and most that had stopped cited the 2020 change.
?Is hCG banned in sport?
For men, yes: WADA's Prohibited List names chorionic gonadotrophin under S2.2.1, and the Legal table below gives the 2026 and 2027 entries.
References
- [fda-pi] Pregnyl (chorionic gonadotropin for injection) Prescribing Information. Organon; revised 03/2025 (DailyMed, read 2026-09-28).
- [fda-pi] Novarel (chorionic gonadotropin for injection) Prescribing Information. Ferring Pharmaceuticals (DailyMed version of 2025-09-25, read 2026-09-28).
- [fda-pi] Ovidrel (choriogonadotropin alfa injection) Prescribing Information. EMD Serono (DailyMed version of 2023-12-28, read 2026-09-28).
- [Human] 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;90(5):2595-602. PMID: 15713727.
- [Human] Hsieh TC, et al. "Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy." J Urol, 2013;189(2):647-50. PMID: 23260550.
- [Human] Madhusoodanan V, et al. "Human Chorionic Gonadotropin monotherapy for the treatment of hypogonadal symptoms in men with total testosterone > 300 ng/dL." Int Braz J Urol, 2019;45(5):1008-1012. PMID: 31408289.
- [Human] Gill GV. "Anabolic steroid induced hypogonadism treated with human chorionic gonadotropin." Postgrad Med J, 1998;74(867):45-6. PMID: 9538490.
- [Human] Menon DK. "Successful treatment of anabolic steroid-induced azoospermia with human chorionic gonadotropin and human menopausal gonadotropin." Fertil Steril, 2003;79 Suppl 3:1659-61. PMID: 12801577.
- [Human] Kobori Y, et al. "Hormonal therapy (hCG and rhFSH) for infertile men with adult-onset idiopathic hypogonadotropic hypogonadism." Syst Biol Reprod Med, 2015;61(2):110-2. PMID: 25518839.
- [Human] Shankar RR, et al. "Corifollitropin Alfa Combined With Human Chorionic Gonadotropin in Adolescent Boys With Hypogonadotropic Hypogonadism." J Clin Endocrinol Metab, 2022;107(7):2036-2046. PMID: 35275602.
- [Human] Tamunopriye J, et al. "Human chorionic gonadotrophin (HCG) stimulation test and testosterone response in children with micropenis." Pediatr Endocrinol Rev, 2014;12(1):42-5. PMID: 25345084.
- [Human] Morley L, et al. "Timing of human chorionic gonadotrophin (hCG) hormone administration in IVF protocols using GnRH antagonists: a randomized controlled trial." Hum Fertil (Camb), 2012;15(3):134-9. PMID: 22812907.
- [Human] Aflatoonian A, et al. "Efficacy of low-dose hCG in late follicular phase in controlled ovarian stimulation using GnRH agonist protocol." Arch Gynecol Obstet, 2012;286(3):771-5. PMID: 22619027.
- [Review] Youssef MA, et al. "Gonadotropin-releasing hormone agonist versus HCG for oocyte triggering in antagonist-assisted reproductive technology." Cochrane Database Syst Rev, 2014;2014(10):CD008046. PMID: 25358904.
- [Human] van der Merwe R, et al. "The bioequivalence of liquid and freeze-dried formulations of recombinant human chorionic gonadotrophin." Curr Med Res Opin, 2004;20(3):397-402. PMID: 15025848.
- [Review] 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;40(3):237-43. PMID: 8527285.
- [Human] Nome RV, et al. "Lowered reference limits for hCG improve follow-up of patients with hCG-producing tumors." Clin Biochem, 2018;52:73-79. PMID: 29198759.
- [Animal] Segal TR, et al. "Superovulation with human chorionic gonadotropin (hCG) trigger and gonadotropin releasing hormone agonist (GnRHa) trigger differentially alter essential angiogenic factors in the endometrium in a mouse ART model†." Biol Reprod, 2020;102(5):1122-1133. PMID: 31995151.
- [Human] Borgert BJ, et al. "The availability of gonadotropin therapy from FDA-approved pharmacies for men with hypogonadism and infertility." Sex Med, 2023;11(2):qfad004. PMID: 37051549.
- [fda-pi] US FDA. List of Approved NDAs for Biological Products That Were Deemed to be BLAs on March 23, 2020 (chorionic gonadotropin: Pregnyl NDA 017692, Novarel NDA 017016, Chorionic Gonadotropin NDA 017067; choriogonadotropin alfa: Ovidrel NDA 021149).
- [fda-pi] US FDA. Avoid Dangerous HCG Diet Products (consumer update; content current as of July 13, 2020).
- [fda-pi] US FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A, Categories 1-3 (updated May 14, 2026): chorionic gonadotropin not listed.
Sources & Citations
Every PubMed citation on this page has been checked against its record. The labels (Pregnyl, Novarel, Ovidrel) were read on DailyMed and FDA's documents at fda.gov on September 28, 2026. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.