What it is
Human chorionic gonadotropin, or hCG, is the hormone that pregnancy tests detect. The placenta makes it in early pregnancy to keep the ovary producing the hormones that sustain the pregnancy. It acts on the same receptor as LH, the pituitary hormone that triggers ovulation in women and tells the testes to make testosterone in men.
That shared action is the basis of its approved medical roles. It is approved in the United States to trigger ovulation in fertility treatment, to stimulate the testes in men whose pituitary does not make enough LH, and to help undescended testicles move down in young boys.
Unlike most substances on this site, hCG is a large protein with sugar chains attached, not a short peptide. The urinary hCG labels state that it has not been shown to be effective for weight loss.
hCG is a heterodimeric glycoprotein of a 92-residue α subunit, common in structure to LH and FSH, and a 145-residue β subunit that confers specificity; both carry N- and O-linked glycans, and a C-terminal extension of the β subunit is reported to prolong its circulation relative to LH. It is a full agonist at the LH/choriogonadotropin receptor (LHCGR), a Gs-coupled receptor on ovarian theca and granulosa-lutein cells and testicular Leydig cells. Activation raises cAMP and drives steroidogenesis; in the pre-ovulatory follicle it induces final oocyte maturation, resumption of meiosis and follicular rupture, and in men it stimulates testosterone production and, indirectly, spermatogenesis.
Pharmacokinetics (Ovidrel label, recombinant hCG 250 µg subcutaneously): peak concentration at 12–24 hours, bioavailability about 40% and a terminal half-life of about 29 hours. Urinary products are dosed in USP units, recombinant product in micrograms; 250 µg recombinant hCG was judged equivalent to 10,000 units of urinary hCG in the trial that supported Ovidrel.
Who made it and when
In 1927 two Berlin gynaecologists, Selmar Aschheim and Bernhard Zondek, found that urine from pregnant women made immature female mice come into heat. That observation became the first reliable pregnancy test, and the substance behind it was later identified as hCG, a hormone made by the placenta.
For decades the medicine was purified from the urine of pregnant women. In the United States, Ferring’s Novarel dates from 1974 and Organon’s Pregnyl from 1976, with other generic versions. A recombinant version made in cultured hamster cells, Ovidrel from EMD Serono, was approved in 2000. In March 2020 US law reclassified all these products as biological products.
Aschheim and Zondek described the gonadotropic activity of pregnancy urine in 1927, the basis of the A-Z bioassay; they attributed it to the pituitary, and later work showed it came from the placenta. Urinary hCG was developed into injectable products; FDA’s deemed-BLA list gives initial NDA approval dates of 1974-01-15 for Novarel (NDA 017016, Ferring) and 1976-10-20 for Pregnyl (NDA 017692, Organon), alongside other urinary products from Fresenius Kabi and others. Ovidrel (choriogonadotropin alfa, NDA 021149, EMD Serono) followed on 2000-09-20.
A transition provision of the Biologics Price Competition and Innovation Act of 2009 provided that on 2020-03-23 approved applications for biological products under section 505 of the FD&C Act would be deemed licences under section 351 of the PHS Act. All hCG and choriogonadotropin alfa applications appear on FDA’s transition list, which gives their former NDA numbers; the current Pregnyl label carries a US biologics licence number. No current compound patent applies to urinary hCG.
What the data say
For its approved fertility uses, hCG has decades of clinical experience and label data behind it. In an IVF trial of about 300 women, the recombinant version triggered egg maturation as well as the standard urinary product. A 2005 study of 29 healthy men given testosterone, which shuts down the body’s own LH, reported that low doses of hCG every other day for three weeks kept testosterone levels inside the testes within the normal range.
The weight-loss story is the opposite. A diet plan known as the Simeons method combined hCG injections with a very-low-calorie diet. Controlled trials, such as a 1976 study of 51 women on a 500-calorie diet, found no extra weight loss from hCG compared with placebo injections on the same diet. A 1995 review of 24 studies concluded there was no scientific evidence that hCG is effective in treating obesity. The FDA has said that any weight lost comes from the severe calorie restriction, not from hCG.
Fertility: Chang et al. (Fertil Steril 2001) randomised 297 ovulatory women undergoing IVF to recombinant hCG 250 µg SC, 500 µg SC or urinary hCG 10,000 USP units IM; mean oocytes retrieved were 13.6, 14.6 and 13.7, with more fertilised oocytes but a trend to more adverse events at 500 µg. The Ovidrel label reports clinical pregnancy in 35.1% per initiated ART cycle and ovulation in 91.9% in ovulation-induction trials.
Male physiology: Coviello et al. (JCEM 2005) gave 29 men testosterone enanthate 200 mg weekly plus hCG 125, 250 or 500 IU every other day or placebo for 3 weeks. LH and FSH fell to 5% and 3% of baseline; intratesticular testosterone ended 25% below, 7% below and 26% above baseline, respectively.
Obesity: Stein et al. (Am J Clin Nutr 1976; n=51 women, double-blind, 32 days) repeated the 500 kcal diet of a 1973 positive study with hCG or placebo injections and found no difference in weight loss, girth or hunger. Lijesen et al. (Br J Clin Pharmacol 1995) scored 8 controlled and 16 uncontrolled trials; of the 12 better-quality studies only one reported benefit, and the authors found no evidence that hCG causes weight loss or fat redistribution.
Regulatory picture
Three separate facts. Approval: hCG is FDA approved, by prescription and by injection, for fertility treatment, certain men with low pituitary hormone output, and undescended testicles in boys. It is not approved for weight loss, and no hCG product is approved for use without a prescription. Compounding: since March 2020 hCG has been regulated as a biological product, and the FDA told pharmacies that biological products cannot be compounded under the usual pharmacy rules; they can only be mixed or diluted under narrow conditions. Enforcement: in 2011 the FDA and the Federal Trade Commission warned seven companies selling “homeopathic” hCG diet drops, and the FDA has warned consumers to avoid hCG diet products.
Approval: approved. Urinary hCG (Pregnyl, Novarel and generics) is labelled for prepubertal cryptorchidism not due to anatomic obstruction, selected hypogonadotropic hypogonadism in males, and ovulation induction in anovulatory women pretreated with gonadotropins; Ovidrel for final follicular maturation in ART and ovulation induction. The urinary hCG labels state in capitals that hCG has not been demonstrated to be effective adjunctive therapy in the treatment of obesity, with no substantial evidence of weight loss beyond caloric restriction or of effects on fat distribution or hunger.
Compounding: recorded as restricted. FDA’s 2020-03-05 notice named human chorionic gonadotropin among four bulk substances affected by the transition and stated that biological products are not eligible for the section 503A and 503B exemptions. FDA’s 2018 guidance on mixing, diluting or repackaging biological products outside the scope of a BLA describes limited conditions for manipulating a licensed product; it does not permit compounding from bulk hCG.
Enforcement: the 2011-12-06 joint FDA and FTC action targeted over-the-counter “homeopathic” hCG products; FDA’s consumer update (2020) states that hCG is not approved for weight loss or for use without a prescription. In sport, WADA’s 2026 list prohibits chorionic gonadotrophin in males under S2.2.1.
