hCG (human chorionic gonadotropin)

Overview

hCG (human chorionic gonadotropin) is the glycoprotein hormone produced by the placenta in pregnancy — the hormone home pregnancy tests detect. Structurally it is a heterodimer of a common alpha subunit (shared with LH, FSH and TSH) and a beta subunit unique to hCG, together about 37 kDa. Pharmacologically it is a luteinizing-hormone (LH) receptor agonist: the Pregnyl label states its action "is virtually identical to that of pituitary LH."

Unlike most entries on this site, hCG is a genuinely approved medicine — but only for a few specific indications. In men it stimulates testicular (Leydig-cell) steroidogenesis, raising intratesticular and circulating testosterone and helping maintain sperm production; in women it serves as the ovulation trigger, driving final egg maturation and follicle rupture and supporting the corpus luteum. It is available as urinary-derived products (Pregnyl, Novarel) and a recombinant product (Ovidrel/Ovitrelle, choriogonadotropin alfa).

The community interest that brings people to this page is mostly off-label: using hCG to keep the testes functioning and preserve fertility during or after testosterone therapy (the "testosterone off-ramp"). That use has a real rationale but only modest supporting evidence, and this page describes it honestly while giving no dosing, protocol, or restart schedule.

Chemistry and structure

The alpha subunit is shared with LH, FSH and TSH; the beta subunit is unique to hCG and gives it LH-like activity with a longer half-life than pituitary LH. It is a protein hormone, not a short defined peptide sequence.

Mechanism of action

• LH-receptor (LHCGR) agonism. hCG binds the same receptor as luteinizing hormone and acts as an LH mimetic — "virtually identical to that of pituitary LH" per the product label. [Human]
• Men — testicular steroidogenesis. It stimulates Leydig cells to produce testosterone, raising intratesticular testosterone and, unlike exogenous testosterone, helping preserve spermatogenesis and testicular volume rather than suppressing them. [Human]
• Women — ovulation trigger. It drives final follicular maturation, resumption of oocyte meiosis and follicle rupture, and maintains the corpus luteum (physiologically, placental hCG sustains the corpus luteum in early pregnancy). [Human]
• Axis level. hCG acts downstream, at the gonad — distinct from GnRH/gonadorelin (upstream, on the pituitary) and from LH/FSH themselves.

Approved uses and evidence

Approved indications (strongest tier). Ovulation induction and the ART ovulation trigger are long-established, FDA-approved uses with decades of data; recombinant and urinary products are comparable. Male hypogonadotropic hypogonadism secondary to pituitary deficiency and prepubertal cryptorchidism are the approved male/pediatric indications. [Human — approved]

Off-label fertility / testicular preservation during or after testosterone (the use that brings most readers here). The evidence is low-to-moderate and off-label: a small 3-week randomized trial (n=29) showed low-dose hCG maintains intratesticular testosterone during testosterone-induced gonadotropin suppression — but on a surrogate endpoint, not live births (Coviello et al., JCEM 2005) [Human, small/surrogate]; a retrospective series (n=26) suggested concomitant hCG preserves semen parameters in men on testosterone therapy (Hsieh et al., J Urol 2013) [Human, retrospective]; and a small retrospective safety series (n=28) examined hCG monotherapy after prior testosterone use (Rainer et al., Cureus 2022) [Human, retrospective]. These support a plausible role but are not proof of preserved live-birth fertility, and none establishes a "restart protocol."

Weight loss — rejected. Since 1975 the FDA label has stated hCG "has not been demonstrated to be effective adjunctive therapy in the treatment of obesity" and "has no known effect on fat mobilization, appetite or sense of hunger, or body fat distribution." OTC/"homeopathic" hCG weight-loss products are illegal (FDA/FTC).

Status and regulation

hCG is an approved medicine for the indications above (urinary Pregnyl/Novarel; recombinant Ovidrel/Ovitrelle). Fertility/testicular-preservation and "TRT restart" uses are off-label; using an approved drug off-label is a clinical decision made with a prescriber, not a self-administration protocol. Products sold as grey-market "research" hCG are not the approved medicine and carry no guarantee of identity, purity, sterility or potency.

WADA status: hCG is on the WADA Prohibited List, class S2, prohibited in males only (in females it does not meaningfully raise blood testosterone), in and out of competition. WADA sport-eligibility is a separate axis from legal status.

Safety

• In women: ovarian hyperstimulation syndrome (OHSS) — sudden ovarian enlargement, ascites, pleural effusion, which can be serious; ovarian cyst rupture; multiple pregnancy in ovulation-induction use (label warnings).
• Arterial thromboembolism is an explicit label warning; the FDA has received reports of pulmonary embolism, stroke, cardiac arrest and death associated with hCG marketed for weight loss.
• In men: gynecomastia and rising estradiol (hCG-driven testosterone is aromatized to estrogen).
• In prepubertal boys: precocious puberty (treatment stopped if signs appear).
• Hypersensitivity/anaphylaxis has been reported, particularly with urinary-derived products; injection-site reactions, headache, edema and mood changes occur.
• Grey-market material: unregulated identity/purity/sterility/potency; none of the approved-use safeguards (indication, supervision, monitoring) apply.

Legal status

hCG is a prescription medicine where approved — obtaining or using it outside a prescription, or using grey-market "research" material, is a different matter from its approved status, and "not specifically banned for X" is not affirmative permission. OTC and "homeopathic" hCG weight-loss products are illegal in the US. Being intended for an unapproved human use does not make research-grade material a lawful medicine. WADA sport-prohibition (S2, males) is separate from legality. This is not legal or medical advice; approval status, scheduling and enforcement differ by country and change over time — verify your own jurisdiction. (Dated 2026-07-19.)

How it compares

• Gonadorelin — synthetic GnRH, acting upstream on the pituitary to release LH/FSH. hCG bypasses that level and stimulates the gonad directly as an LH mimetic.
• Kisspeptin — acts even further upstream, driving GnRH release; an experimental reproductive-axis tool, not an approved gonadal stimulator like hCG.
• Exogenous testosterone — raises blood testosterone but suppresses LH/FSH and shrinks testicular function; the off-label rationale for hCG is precisely to counter that suppression.

Common misconceptions

• "hCG is a peptide." It is a ~37 kDa glycoprotein hormone (alpha/beta heterodimer), not a small peptide.
• "hCG is FDA-approved to restart testosterone / preserve fertility on TRT." Those uses are off-label; the approved male indication is hypogonadotropic hypogonadism secondary to pituitary deficiency (plus prepubertal cryptorchidism). The supporting evidence is small or surrogate-endpoint.
• "hCG helps you lose weight / burn fat." The FDA label (since 1975) says it has not been shown effective and has no known effect on fat, appetite or hunger; OTC/"homeopathic" weight-loss hCG is illegal.
• "hCG is the same as LH." It is an LH mimetic on the same receptor; only the alpha subunit is shared with LH, and its beta subunit and longer half-life differ.
• "Research hCG is the same as the pharmacy product." Grey-market material is unregulated and not the approved medicine; approved-use safety framing does not transfer.