HCG peptide: what it is, how it works and the research
HCG (human chorionic gonadotropin) is a glycoprotein hormone, not a small peptide: two subunits (alpha 92 amino acids, beta 145) acting on the LH receptor, studied for intratesticular testosterone maintenance, spermatogenesis recovery and ovulation triggering. "HCG peptide" is the search term, not the chemistry. PrymaLab supplies it as HCG 5000iu and HCG 10000iu for research use.
- Size: alpha subunit of 92 amino acids (shared with LH, FSH, TSH) plus a unique 145-residue beta subunit.
- Class: glycoprotein hormone (gonadotropin), measured in international units rather than milligrams.
- Studied for: intratesticular testosterone on TRT (Coviello 2005), spermatogenesis (Wenker 2015), hypogonadism (Habous 2018), ovulation triggering.
- Storage: lyophilized vial refrigerated; reconstituted solution refrigerated and used within the study window.
- Forms and sizes at PrymaLab: HCG 5000iu and HCG 10000iu; related: Gonadorelin 2mg and HMG 75IU.
- Regulatory: approved drug forms exist (Pregnyl, Novarel, Ovidrel); the FDA states HCG is not approved for weight loss.
| Feature | HCG | Gonadorelin | HMG |
|---|---|---|---|
| Molecule | Glycoprotein hormone, 237 residues across two subunits | GnRH decapeptide (10 amino acids) | Urinary menotropins with FSH and LH activity |
| Acts on | LH/CG receptor on Leydig and granulosa cells | GnRH receptor on pituitary gonadotrophs | FSH and LH receptors |
| Measured in | IU | mg | IU |
| Forms at PrymaLab | HCG 5000iu, HCG 10000iu | Gonadorelin 2mg, Gonadorelin 10mg Nasal Spray | HMG 75IU, hMG pen (150IU) |
The peptide reconstitution calculator converts vial contents and water volume into concentration per unit volume. For where the line between a peptide and a protein sits, see what counts as a peptide.
Also known as: human chorionic gonadotropin, hCG
Quick answer: HCG peptide
The phrase "HCG peptide" is a search convention rather than a chemical description. Human chorionic gonadotropin is a glycoprotein hormone of two subunits and 237 amino acids in total, produced by the placenta, and it acts on the same receptor as luteinizing hormone. Because it is far larger than the 40-residue line that separates peptides from proteins in US regulation, it is handled differently from the short synthetic peptides on this site. This guide covers what HCG is, the receptor it acts on, what named studies measured, the FDA-approved uses and the HCG diet warning. PrymaLab supplies HCG 5000iu and HCG 10000iu for research use only; the peptide reconstitution calculator converts vial contents and water volume into concentration per unit volume.
Disclaimer: This article is an educational review of published studies and does not constitute medical advice. HCG is a prescription medication with major hormonal effects, and the clinical studies described here were run under medical supervision. PrymaLab supplies HCG for laboratory research use only, not for human or veterinary use.
What is the HCG peptide?
HCG Peptide — Quick Definition
Human chorionic gonadotropin (hCG) is a glycoprotein hormone composed of an alpha and a beta subunit, naturally produced by the placenta during pregnancy. HCG is uniquely sold for research use only purposes by many online stores. In clinical medicine, the hCG peptide is prescribed to support male testosterone production, induce ovulation in women, and manage select endocrine conditions like hydatidiform mole(molar pregnancy), gestational trophoblastic disease, or choriocarcinoma. It is not a traditional peptide but is often grouped with peptide therapies in the wellness space.
Human chorionic gonadotropin occupies a unique position in modern endocrinology. Although the wellness industry often refers to it as an hCG peptide, its cell-level structure is that of a heterodimeric glycoprotein with a cell-level weight of about 36.7 kilodaltons. The alpha subunit, consisting of 92 amino acids, is identical to the alpha chain shared by luteinizing hormone lh, follicle-boosting hormone, and thyroid-boosting hormone. The beta subunit, however, is unique to hCG and contains an more 24-amino-acid carboxy-terminal extension not found in LH, giving the molecule distinct pharmacokinetic properties (Ezcurra & Humaidan, 2014).
Grasp the hCG peptide begins with appreciating how it interacts with the body. The hormone binds to the LH/hCG receptor (LHCGR) found on Leydig cells in the male testes and on granulosa and theca cells in the female ovary. In men, this binding boosts intratesticular testosterone synthesis. In women, it mimics the natural LH surge that triggers ovulation and supports the corpus luteum during early pregnancy. The molecule’s eight glycosylation sites—which can influence the development of antibodies—compared to only three on LH—give hCG a under-skin half-life of 32 to 33 hours, far exceeding LH’s half-life of about 30 minutes after intravenous use. This extended activity makes hCG an ideal pharmacological analog to LH for clinical uses.
Production of hCG, often called the pregnancy hormone, begins almost immediately after embryo implantation, with hCG levels measured in mIU/mL or IU/L doubling about every 48 to 72 hours during early pregnancy to reflect increasing gestational age. This rapid rise is the natural basis for home pregnancy tests, clinical blood test monitoring to rule out an ectopic pregnancy, prenatal screening for down syndrome based on the date of the last menstrual period, a diagnostic urine test, and various diagnostic hCG tests. Beyond reproduction, hCG has been studied for roles in angiogenesis, germ cell tumors, screening for Down syndrome, diagnosing ectopic pregnancy, immune tolerance at the maternal-fetal interface, and hormonal tuning in both sexes. The sections that follow explore each of these clinical uses in evidence-based detail, covering everything from the testosterone studies to the controversial hCG diet and the control changes that have reshaped access to this important hormone.
The growing popularity of hCG in men’s health clinics reflects a broader shift toward hormone tuning rather than simple replacement. Where earlier decades saw hCG used almost exclusively in fertility medicine, clinical studies have since examined exogenous testosterone combined with hCG to test whether testicular function is preserved during testosterone-induced suppression.
What an international unit of hCG measures
hCG is labelled in international units because its potency is defined by biological activity against a reference preparation, not by weight, so any conversion between units and milligrams depends on the assay behind it. A WHO collaborative study of the International Standard for pituitary FSH, a glycoprotein hormone whose alpha subunit is identical to that of hCG (Fournier et al. 2015), shows how large the differences between methods can be. Twenty-seven laboratories in 13 countries assayed the standard by bioassays, receptor assays and immunoassays (Storring et al. 1989). The in vivo bioassay estimates were consistent within and between laboratories, at a combined 79.9 IU per ampoule; in vitro bioassays and receptor assays were also consistent with each other but gave 31.2 IU; and 19 immunoassay systems disagreed, ranging from 5 to 31 IU (Storring et al. 1989). The WHO assigned 80 IU per ampoule from the in vivo bioassay, because that assay best identifies and defines the hormone, and noted that immunoassay kits would have to be recalibrated (Storring et al. 1989).
Immunoassays for hCG face a further problem, because the hormone exists in intact, nicked, free-subunit and fragment forms. Birken and colleagues found in 2003 that the standards then in use for hCG and its subunits held substantial amounts of contaminating variants and other impurities (Birken et al. 2003). They prepared new reference reagents for intact hCG, nicked hCG, the free alpha and beta subunits, nicked beta subunit and the beta-core fragment, characterized each by amino acid and sequence analysis, carbohydrate composition and electrophoresis, and set the concentrations by amino acid analysis (Birken et al. 2003).
Regular and hyperglycosylated hCG
The guide treats hCG as one molecule, but the literature describes a family. Cole's 2009 review distinguished regular hCG, hyperglycosylated hCG and the free beta-subunit of hyperglycosylated hCG, and contrasted this with LH and the other glycoprotein hormones, each of which exists as a single molecule (Cole 2009). Regular hCG is made by fused villous syncytiotrophoblast cells and has long been known to promote progesterone production by the corpus luteum, although that function explains only about three weeks of its production across a pregnancy; later work assigned it roles in trophoblast differentiation and in fetal nutrition through angiogenesis of the myometrial spiral arteries (Cole 2009). The hyperglycosylated form is made by invasive extravillous cytotrophoblast cells and acts on those cells as an autocrine factor, inhibiting apoptosis and promoting invasion at implantation and in invasive hydatidiform mole and choriocarcinoma (Cole 2009).
Glycosylation is what separates these forms. The alpha subunit carries two N-glycosylation sites and the beta subunit two N-glycosylation and four O-glycosylation sites, and Fournier and colleagues reported that the glycosylation state of hCG varies with the stage of pregnancy, the producing cell and disease (Fournier et al. 2015). Hyperglycosylated hCG is high in maternal blood during the early first trimester, while total hCG peaks at around 8 to 10 weeks of gestation (Fournier et al. 2015).
Mechanism of action: how HCG works
The mechanism of action of the hCG peptide revolves around its power to start the LH/hCG receptor with about five-fold greater potency than native luteinizing hormone lh. When hCG binds this G-protein-coupled receptor, it triggers a cyclic AMP signaling cascade that finally drives steroidogenesis—the enzymatic conversion of cholesterol into steroid hormones including testosterone, progesterone, and estradiol. This single pathway explains why human chorionic gonadotropin for men can raise testosterone levels and why it serves as a key fertility tool for women.
Mechanism in Men: Testosterone and Spermatogenesis
In the male body, the hCG peptide acts directly on Leydig cells within the testes. Leydig cells are responsible for producing roughly 95 percent of circulating testosterone, but they need boost from LH—or its analog, hCG—to function. When a man begins testosterone replacement therapy, the hypothalamic-pituitary-gonadal axis detects elevated systemic testosterone and reduces its own GnRH and LH secretion through negative feedback. Intratesticular testosterone levels can plummet by as much as 94 percent within weeks of starting TRT, severely impairing spermatogenesis and possibly leading to azoospermia and testicular atrophy (Coviello et al., 2005). In studies that gave exogenous hCG alongside testosterone, intratesticular testosterone was maintained (Coviello et al., 2005), and testicular size and sperm production were preserved (Hsieh et al., 2013).
Mechanism in Women: Ovulation and Luteal Support
In the female fertility system, hCG serves a different but equally important role. During a natural menstrual cycle, the pituitary gland releases a surge of LH that triggers the release of a mature egg from the ovarian follicle. In helped fertility technology, injectable hCG replaces this natural LH surge: hCG starts the final maturation of the oocyte and rupture of the follicle, and ovulation follows about 36 to 40 hours later. After ovulation, hCG also supports the corpus luteum, the progesterone-producing structure that prevents menstruation and sustains early pregnancy until the placenta assumes hormonal control at about 10 to 12 weeks of gestation.
FDA-approved uses of HCG: indications, brands and prescribing facts
The Food and Drug Use has approved hCG for three specific clinical signs: induction of ovulation in anovulatory women after FSH priming (Pregnyl, Novarel, Ovidrel), hypogonadotropic hypogonadism in men with documented LH deficiency (Pregnyl, Novarel), and prepubertal cryptorchidism in boys with undescended testes not due to an anatomical cause (Pregnyl, Novarel). These approvals are limited to injectable forms available only by prescription—no oral, sublingual, or homeopathic hCG product has ever got FDA approval for any purpose. The labels set out their own regimens, which are not reproduced here.
Pregnyl and Novarel are urinary-derived hCG products extracted and purified from the urine of pregnant women, supplied as freeze-dried powder in 10,000 IU vials that need mixing with sterile water before use. Ovidrel, by contrast, is a recombinant hCG product manufactured using Chinese hamster ovary cell technology and supplied as a ready-made solution. The recombinant form offers more consistent batch-to-batch potency and removes the risk of urinary-derived contaminants, though it comes at a higher cost. All three products are prescription-only.
Off-label, hCG has been studied as an adjunct to testosterone replacement therapy, for fertility preservation and testicular atrophy, and as monotherapy in men with hypogonadal symptoms, including men whose testosterone levels exceed the 300 ng/dL threshold set by the American Urological Association. These off-label uses do not carry FDA approval.
HCG in women: fertility, trigger shots and reproductive research
For women, the hCG peptide plays an indispensable role in helped fertility technology and ovulation induction. Its power to mimic the LH surge makes it the standard trigger agent in both in-vitro fertilization (IVF) and intrauterine insemination (IUI) protocols.
The HCG Ovulation Trigger: Mechanism
In controlled ovarian stimulation with FSH-containing drugs such as Gonal-F or Follistim, hCG is used in place of the natural LH surge once transvaginal ultrasound shows the leading follicle at about 18 to 20 millimeters, before egg retrieval in IVF or timed intercourse. Urinary-derived (Pregnyl, Novarel) and recombinant (Ovidrel) products are both used for this purpose. The trigger starts the final maturation of the oocyte, resumption of meiosis, cumulus expansion, and rupture of the follicular wall—the coordinated cascade we recognize as ovulation.
Luteal Phase Support and Early Pregnancy
After ovulation, the corpus luteum needs continued boost to keep progesterone production, which is essential for the uterine lining, endometrial receptivity, and embryo implantation. In natural conception, the implanting embryo itself begins producing hCG within days of attachment, often before a missed period, signaling the corpus luteum to continue its hormonal output. In IVF cycles, exogenous hCG or progesterone use may be prescribed during the luteal phase to bridge the gap until the developing placenta assumes progesterone production at about 10 to 12 weeks of gestation. This dual role—triggering ovulation and then sustaining the hormonal environment of early pregnancy—makes hCG one of the most versatile molecules in fertility endocrinology.
The HCG diet: evidence, risks and FDA warnings
The hCG diet remains one of the most controversial topics linked with the hCG peptide, and any full discussion of human chorionic gonadotropin must address it directly. Despite widespread consumer interest, the scientific evidence and control position are clear: the HCG diet does not work as advertised, and FDA-banned OTC products continue to pose genuine health risks.
Origins: Simeons’ 1954 Proposal
British endocrinologist Albert T. W. Simeons first proposed hCG as a weight loss tool in 1954, publishing the scheme in his book “Pounds and Inches: A New Approach to Obesity.” His scheme combined hCG with a severely restricted 500-calorie-per-day diet. Simeons claimed the hormone mobilized stored fat for energy, prevented hunger despite the extreme calorie deficit, and protected lean muscle mass.
What Does the Clinical Evidence Show?
Multiple controlled clinical trials conducted between the 1970s and the 2010s have definitively refuted Simeons’ claims. Studies comparing hCG injections to placebo injections in participants on identical 500-calorie diets consistently found no major difference in weight loss, fat distribution, hunger levels, or mood between the two groups. A 1995 meta-test and later reviews confirmed that any weight loss saw on the hCG diet is attributable entirely to the severe calorie restriction, not to the hormone itself. The hCG peptide does not enhance fat mobilization, suppress appetite, or prevent the muscle loss that inevitably accompanies a very-low-calorie diet (VLCD).
These findings are important because the hCG diet continues to be marketed aggressively online, often using misleading testimonials and pseudo-scientific language. Consumers searching for hCG for weight loss deserve accurate data: a 500-calorie-per-day diet will produce rapid weight loss in virtually anyone, but the results are unsustainable, and the extreme restriction carries major body and nutritional risks regardless of whether hCG is added.
FDA and FTC Enforcement Actions
The FDA’s position is unequivocal: “There are no FDA-approved HCG products for weight loss. HCG has not been showed to be effective therapy in the treatment of obesity.” The agency has joined with the Federal Trade Commission to issue warning letters to manufacturers of over-the-counter homeopathic hCG drops, pellets, and sprays—products that often contain no actual hCG hormone despite their labeling claims. These products are considered illegal unapproved new drugs and misbranded drugs under federal law. The FDA has also got reports of serious adverse events in people using prescription hCG injections off-label for weight loss, including pulmonary embolism, cerebrovascular events, depression, cardiac arrest, and death. The very-low-calorie component of the diet independently increases the risk of gallstone formation, electrolyte imbalances, and cardiac arrhythmias.
Bottom Line on HCG for Weight Loss: No credible scientific evidence supports the use of hCG for weight care. The FDA explicitly advises consumers to avoid all over-the-counter HCG weight loss products. Any weight loss on the HCG diet is due to the dangerous 500-calorie restriction, not the hormone.
What the HCG studies measured
The studies cited in this guide measured different things. Coviello and colleagues measured intratesticular testosterone in healthy men during testosterone-induced gonadotropin suppression. Hsieh and colleagues measured sperm count and testicular volume in men on testosterone therapy. Wenker and colleagues measured recovery of spermatogenesis after testosterone use. Habous and colleagues compared serum testosterone on hCG and on clomiphene in hypogonadal men, and Madhusoodanan and colleagues measured serum testosterone and symptoms in 20 men given hCG alone.
Studies of fertility uses in women follow a different design: hCG is given once, to replicate the LH surge, and timing rather than repeated administration is the variable studied.
Handling in the lab
Urinary-derived hCG products such as Pregnyl and Novarel are supplied as a freeze-dried powder that is dissolved in a suitable diluent such as sterile water before use. Concentration is the vial’s content divided by the volume of diluent added. Swirl the vial gently until the powder is fully dissolved; avoid vigorous shaking, as this can denature the protein. Once mixed, the solution should be clear and free of particulate matter. Recombinant hCG (Ovidrel) is supplied already in solution. Storage after dissolution is covered in the next section.
How HCG is stored: shelf life and stability
Proper hCG storage directly impacts the potency and safety of the medication. Because hCG is a protein-based hormone, it is sensitive to heat extremes, light exposure, and microbial contamination. The manufacturer’s storage conditions are summarized below.
| Product Form | Storage Condition | Heat | Shelf Life |
|---|---|---|---|
| Unreconstituted powder (Pregnyl, Novarel) | Room heat, protected from light | 15–30 °C (59–86 °F) | Until expiration date on label |
| Mixed solution | Refrigerated | 2–8 °C (36–46 °F) | Up to 30 days |
| Ovidrel (recombinant, in solution) | Refrigerated (may store at room temp up to 30 days before use) | 2–8 °C (36–46 °F) | Until expiration date |
Never freeze hCG in any form, as freezing destroys the protein structure and renders the hormone inactive. Mixed hCG should be inspected before use for discoloration, cloudiness, or particulate matter—any of these signs show breakdown and the vial should be discarded. Store all hCG products away from direct sunlight. Proper storage preserves the hormone’s activity.
Side effects, safety profile and contraindications of HCG
Like any hormone, hCG has reported adverse effects. Most reported effects are mild and self-limiting, but rare serious complications exist. The Madhusoodanan et al. (2019) monotherapy study recorded no adverse events across 20 patients over six months.
Common Side Effects
Reported effects include injection-site pain, redness or swelling (very common); headache, fatigue, and water retention and bloating (common); and mood swings, irritability, restlessness or insomnia (occasional).
Serious Side Effects (Rare)
In women getting hCG for fertility treatment, ovarian hyperstimulation syndrome (OHSS) is the most major risk. OHSS occurs when the ovaries overrespond to boost, producing multiple large follicles and releasing vasoactive substances that cause fluid shifts from the vascular compartment into the abdomen and lungs. Symptoms range from mild abdominal discomfort and bloating to severe pelvic pain, rapid weight gain, shortness of breath, and decreased urine output. Severe OHSS needs hospitalization and can be life-threatening. Risk is highest in women with polycystic ovary syndrome (PCOS), those carrying twins or triplets, or those who develop many follicles during boost.
In men, prolonged use of high-dose hCG can theoretically increase estradiol levels through aromatization of elevated intratesticular testosterone, possibly causing gynecomastia. Blood clot formation, including deep vein thrombosis and pulmonary embolism, has been reported in rare case studies linked with hCG use, very in the context of the very-low-calorie HCG diet.
Contraindications
HCG therapy is contraindicated in people with hormone-sensitive cancers (prostate, breast, ovarian cancer, testicular cancer, or germ cell tumors), precocious puberty, known hypersensitivity to hCG or any component of the form, and untreated thyroid or adrenal gland disorders.
HCG in bodybuilding contexts: what the literature says
Within the bodybuilding and fitness community, hCG is used in post-cycle therapy after anabolic steroid courses. Anabolic androgenic steroids suppress the hypothalamic-pituitary-gonadal axis, often resulting in severely reduced natural testosterone production and testicular atrophy, and the rationale offered for hCG is that it acts on Leydig cells directly while pituitary LH output is suppressed.
No randomized trial has tested hCG in people using anabolic steroids. The closest published evidence is Wenker and colleagues’ study, in which azoospermic men recovering from exogenous testosterone use regained sperm levels of 22 million per milliliter within a mean of four months on hCG-based combination therapy (Wenker et al., 2015), and the Coviello study, in which concurrent low-dose hCG prevented the 94 percent decline in intratesticular testosterone seen with exogenous testosterone alone.
Anabolic steroid use without medical supervision carries major health risks, and hCG is not a solution to them. Up to 10 percent of men may remain azoospermic even with aggressive pharmacological intervention.
HCG itself can raise estradiol through intratesticular aromatization, with reported estrogenic side effects such as water retention and gynecomastia.
HCG legal status and regulatory changes
The control landscape for buying hCG has changed dramatically in recent years, and anyone searching to buy hCG needs to understand the current legal framework. The most major shift occurred on March 23, 2020, when provisions of the Biologics Price Competition and Innovation Act of 2009 (BPCIA) took effect, reclassifying hCG from a drug to a biologic. This reclassification had immediate and far-reaching results for both providers and patients.
The 2020 Biologics Reclassification
Under the BPCIA, hCG was reclassified as a biologic because it is extracted from or synthesized from natural sources. This designation means that compounding pharmacies operating under Sections 503A and 503B of the Federal Food, Drug, and Cosmetic Act can no longer legally compound hCG. Prior to March 2020, compounded hCG was widely available through specialty and telemedicine pharmacies at relatively affordable prices. After the reclassification, patients were forced to transition to brand-name manufactured products, which are greatly more expensive and subject to supply constraints. The practical effect has been reduced access and increased cost for the thousands of men who relied on compounded hCG as part of their testosterone therapy or fertility preservation protocols.
What Products Are Still Available?
The approved products are Pregnyl (Organon) and Novarel (Ferring), both urinary-derived in 10,000 IU vials, and Ovidrel (EMD Serono), which is recombinant; all three are prescription only. Over-the-counter “homeopathic” HCG drops and pellets contain no real hCG and are not legally sold in the US.
Oral HCG drops, sprays and pellets either contain no actual hCG hormone or are being sold in violation of federal law, and the FDA has taken enforcement action against many of their vendors. For human use, hCG is dispensed only on prescription by a licensed pharmacy.
HCG vs other hormone therapies: a clinical comparison
This section compares hCG with other hormone therapies studied for testosterone and fertility. Several pharmaceutical alternatives address overlapping clinical needs, each with distinct mechanisms, benefits, and limitations. The following comparison helps contextualize where hCG fits within the broader treatment landscape.
| Therapy | Mechanism | Key Advantage | Key Limitation |
|---|---|---|---|
| HCG | LH/hCG receptor agonist on Leydig cells | Preserves fertility and testicular size | Needs injections; cost increased post-2020 |
| Clomiphene citrate (Clomid) | SERM — blocks estrogen feedback at hypothalamus | Oral use; boosts natural LH/FSH | Can cause visual disturbances; variable response |
| Enclomiphene | Selective SERM (trans-isomer of clomiphene) | More targeted; fewer side effects than CC | Limited long-term data; emerging therapy |
| Testosterone (TRT) | Direct exogenous testosterone replacement | Reliable T rise; multiple supply forms | Suppresses fertility; risk of polycythemia/atrophy |
| Gonadorelin (GnRH analog) | Boosts pituitary LH and FSH release | Preserves natural HPG axis signaling | Needs pulsatile dosing; short half-life |
For men prioritizing fertility, hCG and clomiphene citrate are the two most often prescribed alternatives to standard TRT. HCG has the advantage of directly boosting Leydig cells regardless of pituitary function, so it acts even in hypogonadotropic hypogonadism, where clomiphene, which depends on pituitary LH, would not. Clomiphene, by contrast, works by enhancing the body’s own LH production through hypothalamic signaling and is taken orally rather than by injection. Gonadorelin, a GnRH analog, has emerged as a compounding other since hCG became unavailable through compounding pharmacies, though it needs more frequent use due to its short half-life and pulsatile dosing requirements.
Clomiphene citrate and enclomiphene act through hypothalamic feedback and depend on an intact pituitary, while hCG bypasses the pituitary and acts directly on the testes. Since the 2020 biologics reclassification removed compounded hCG, brand-name products have become more expensive, prompting some clinics to explore gonadorelin or enclomiphene as more affordable alternatives despite their thinner evidence base.
What the clinical evidence says about HCG
The clinical foundation for hCG use rests on decades of research spanning fertility medicine, andrology, and endocrinology. The following studies represent the most influential evidence informing current hCG prescribing practices.
| Study | Year | Design | Key Finding |
|---|---|---|---|
| Coviello et al., J Clin Endocrinol Metab | 2005 | Controlled, eugonadal men on TRT | Low-dose hCG kept intratesticular T (only 7% decline vs 94% without) |
| Hsieh et al., J Urol | 2013 | Retrospective, men on TRT + hCG | Concomitant hCG preserved spermatogenesis at 1-year follow-up |
| Wenker et al., J Sex Med | 2015 | Multi-institutional, post-TRT azoospermia | hCG-based therapy + adjuncts restored sperm to 22M/mL in 4 months mean |
| Habous et al., BJU Int | 2018 | Randomized, 282 hypogonadal men | 94 men on hCG: significant T increase at 1 and 3 months |
| Lee & Ramasamy, Transl Androl Urol | 2018 | Review + algorithm | Proposed treatment algorithm stratified by fertility timeline |
| Madhusoodanan et al., Int Braz J Urol | 2019 | Retrospective, 20 men, hCG monotherapy | T improved 49.9% (362 → 520 ng/dL, p=0.006); 50% symptom gain; no AEs |
The largest body of data comes from studies of hCG as an adjunct to testosterone therapy, with smaller studies of monotherapy in hypogonadal men. In women, hCG has been used as an ovulation trigger in IVF and IUI programs for decades.
HCG drops vs injections: what the evidence shows
One of the most common questions about the hCG peptide involves the difference between hCG drops and hCG injections. The answer is straightforward and supported by both pharmacology and control science: only injectable hCG contains real human chorionic gonadotropin, and only injectable forms are capable of raising blood levels of the hormone to treatment levels.
HCG is a large glycoprotein molecule of about 36.7 kilodaltons. Proteins of this size cannot survive the acidic environment of the stomach or be absorbed intact through the oral or sublingual mucosa. Oral and sublingual hCG drops, even if they contained actual hCG at the time of manufacture, would be broken down by digestive enzymes before reaching the bloodstream. Most hCG drops sold over the counter are labeled as homeopathic preparations, meaning they are so highly diluted that they contain mainly no measurable hCG. The FDA has confirmed that “only injections can raise blood levels of hCG” and that homeopathic OTC products are illegal.
HCG drops, pellets and sprays marketed online have no demonstrated effect and may contain unlisted, possibly harmful ingredients.
Frequently asked questions about the HCG peptide
What is HCG peptide?
"HCG peptide" is the common search term for human chorionic gonadotropin, a glycoprotein hormone made by the placenta. It is not a short peptide: it has an alpha subunit of 92 amino acids and a beta subunit of 145, and it acts on the LH receptor. It is studied for intratesticular testosterone, spermatogenesis and ovulation triggering. PrymaLab supplies HCG 5000iu and HCG 10000iu for research use.
Is HCG a peptide or a hormone?
HCG is a hormone, specifically a glycoprotein hormone of the gonadotropin family. At 237 amino acids across two glycosylated subunits it sits well above the 40-residue limit that US regulation uses to separate peptides from proteins (see what counts as a peptide), which is why it is dosed in international units and regulated as a biologic. The "peptide" label comes from search habits, not from its chemistry.
What did the HCG studies measure?
Coviello et al. measured intratesticular testosterone during testosterone-induced suppression: with low-dose hCG the fall was limited, and at the higher dose it rose 26 percent above baseline. Madhusoodanan et al. measured serum testosterone in 20 men given hCG alone; Habous et al. (2018) compared hCG with clomiphene in hypogonadal men; Wenker et al. (2015) measured recovery of spermatogenesis after testosterone use.
What is the difference between HCG and gonadorelin?
They act at different levels. Gonadorelin is synthetic GnRH, a 10-amino-acid peptide that acts on the pituitary to release LH and FSH. HCG is a 237-residue glycoprotein that bypasses the pituitary and acts directly on the LH receptor in the testis or ovary. PrymaLab supplies Gonadorelin 2mg, a Gonadorelin 10mg Nasal Spray and HMG 75IU alongside HCG 5000iu and HCG 10000iu for research use.
Does the HCG diet work?
Simeons’ 1954 scheme paired HCG with a 500-calorie diet. Controlled trials found that HCG added nothing to the weight loss produced by the diet itself, a conclusion reached by the Lijesen et al. meta-analysis in 1995 (British Journal of Clinical Pharmacology 40(3):237-243), which pooled 14 randomised controlled trials covering 605 people and found no scientific evidence that HCG causes weight loss, redistributes fat, staves off hunger or induces a feeling of well-being, and the FDA states that HCG is not approved for weight loss and that over-the-counter HCG diet products are illegal.
What is the hCG peptide used for?
HCG is FDA-approved for three uses: inducing ovulation in women with infertility, treating selected cases of male hypogonadotropic hypogonadism, and managing prepubertal cryptorchidism. Off-label, it has been studied alongside testosterone replacement therapy for fertility preservation and testicular atrophy.
Is HCG FDA-approved for weight loss?
No. The FDA has explicitly stated that there are no FDA-approved HCG products for weight loss. Clinical studies show that any weight loss on the HCG diet comes solely from the 500-calorie-per-day restriction, not from the hormone itself. OTC homeopathic HCG products are considered illegal by the FDA.
What did the testosterone studies find?
In healthy men whose gonadotropins were suppressed with exogenous testosterone, low-dose hCG limited the fall in intratesticular testosterone (Coviello et al., 2005). In 20 hypogonadal men given hCG alone, serum testosterone rose 49.9 percent over six months (Madhusoodanan et al., 2019).
Over what period did testosterone change in the hCG studies?
In Habous et al. (2018), serum testosterone was significantly higher at one and three months; in Madhusoodanan et al. (2019), the rise was measured over a median of six months; and in Wenker et al. (2015), spermatogenesis recovered within a mean of four months.
Can you still buy compounded hCG?
Since March 23, 2020, the Biologics Price Competition and Innovation Act reclassified hCG as a biologic. Compounding pharmacies under sections 503A and 503B can no longer legally compound hCG. Only brand-name products like Pregnyl, Novarel, and Ovidrel remain available by prescription.
What is the difference between urinary-derived and recombinant hCG?
Urinary-derived hCG products like Pregnyl and Novarel are extracted from the urine of pregnant women and supplied as freeze-dried powder needing mixing. Recombinant hCG, sold as Ovidrel, is produced using recombinant DNA technology and is supplied as a solution with more consistent potency.
Does hCG help preserve muscle during weight loss?
No credible scientific evidence supports the claim that hCG preserves muscle mass during calorie restriction beyond what a placebo would provide. Multiple controlled studies have found identical weight loss and body makeup outcomes between hCG and placebo groups on the same very-low-calorie diet.
How should hCG be stored after reconstitution?
Unreconstituted hCG powder should be stored at controlled room heat between 15 and 30 degrees Celsius (59 to 86 degrees Fahrenheit). After mixing with sterile water, the solution must be refrigerated at 2 to 8 degrees Celsius (36 to 46 degrees Fahrenheit) and used within 30 days.
Key takeaways on the HCG peptide
Human chorionic gonadotropin is one of the most extensively studied hormones in clinical medicine, with research spanning male testosterone, female fertility, and fertility endocrinology. It acts as a potent LH receptor agonist with a half-life of 32 to 33 hours, stimulating intratesticular testosterone production and triggering ovulation. In healthy men given exogenous testosterone, low-dose hCG limited the decline in intratesticular testosterone (Coviello et al., 2005), and in a 20-man monotherapy study serum testosterone rose by nearly 50 percent with no reported adverse events (Madhusoodanan et al., 2019).
Equally important is grasp what hCG cannot do. The hormone is not an effective weight loss agent, and the FDA has explicitly stated that no hCG product is approved for weight care. Over-the-counter drops, pellets, and sprays contain no real hCG and are considered illegal by federal authorities. Since March 2020, compounded hCG is no longer available due to biologics reclassification, leaving brand-name products like Pregnyl, Novarel, and Ovidrel as the only legitimate sources.
The regulatory picture has changed: with compounded hCG no longer available and brand-name prices rising, some clinics have turned to gonadorelin and enclomiphene. PrymaLab supplies HCG for laboratory research use only.
References
1. Ezcurra D, Humaidan P. A review of luteinising hormone and human chorionic gonadotropin when used in helped fertility technology. Reprod Biol Endocrinol. 2014;12:95. doi:10.1186/1477-7827-12-95
2. Lee JA, Ramasamy R. Signs for the use of human chorionic gonadotropic hormone for the care of infertility in hypogonadal men. Transl Androl Urol. 2018;7(Suppl 3):S348–S352. doi:10.21037/tau.2018.04.11
3. 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. doi:10.1590/S1677-5538.IBJU.2019.0132
4. Coviello AD, et al. Low-dose human chorionic gonadotropin keeps intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab. 2005;90(5):2595–2602. doi:10.1210/jc.2004-0802
5. Hsieh TC, et al. Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy. J Urol. 2013;189(2):647–650. doi:10.1016/j.juro.2012.09.043
6. Wenker EP, et al. The Use of HCG-Based Mix Therapy for Healing of Spermatogenesis after Testosterone Use. J Sex Med. 2015;12(6):1334–1337. doi:10.1111/jsm.12890
7. Habous M, et al. Clomiphene citrate and human chorionic gonadotropin are both effective in restoring testosterone in hypogonadism: a short-course randomized study. BJU Int. 2018;122(5):889–897. doi:10.1111/bju.14401
8. U.S. Food & Drug Use. Questions and Answers on HCG Products for Weight Loss. FDA.gov. Accessed July 2025.
9. U.S. Food & Drug Use. Avoid Dangerous HCG Diet Products. FDA.gov. Accessed July 2025.
10. Simeons ATW. Pounds and Inches: A New Approach to Obesity. 1954.
11. Pregnyl (chorionic gonadotropin for injection, USP) Prescribing Data. Organon LLC. Revised 2023.
12. U.S. Food & Drug Use. Notice to Compounders: Changes that Affect Compounding as of March 23, 2020. FDA.gov.
Michael Phelps
Michael is an Air Force veteran and the Marketing Director at PrymaLab. With a specialized background in biochemistry and over 10 years in the biotech industry, he applies military-grade precision to research standards and quality control. Michael is dedicated to bridging the gap between complex scientific studies and practical use, providing accurate, science-backed data on peptides.
