hCG

What is hCG?

Human chorionic gonadotropin (hCG) is a hormone made by the placenta in early pregnancy. It is the hormone that home pregnancy tests detect. Strictly speaking it is a glycoprotein, a protein with sugar chains attached, rather than a short peptide. It appears in peptide directories because it is injected and often used alongside peptide drugs.

hCG was identified in the 1920s, and hormone purified from urine has been used in medicine for most of the last century. In the US it is sold as Pregnyl and Novarel, which are purified from urine, and as Ovidrel, a recombinant version made in cell culture. Approved uses include ovulation induction, hypogonadotropic hypogonadism in men and prepubertal cryptorchidism (undescended testes). Its best-known off-label use today is in men on testosterone replacement therapy (TRT), who take it to keep the testes working and to protect fertility.

How hCG works

In men, the pituitary gland releases luteinizing hormone (LH), which tells the testes to make testosterone. hCG looks enough like LH to press the same button. When a man takes testosterone from outside, his brain senses plenty of hormone and stops sending LH. The testes go quiet, shrink and make fewer sperm. hCG skips the brain and signals the testes directly, so it keeps them active even when the brain's signal is switched off.

In women, the same LH-like signal triggers the final maturation and release of an egg. That is why hCG is used as the "trigger shot" in fertility treatment.

In more precise terms, LH and hCG share one receptor, the LH/choriogonadotropin receptor (LHCGR), a G protein-coupled receptor found on Leydig cells in the testis and on cells of the ovarian follicle.⁵ Men born with inactivating mutations in this receptor have Leydig cell hypoplasia and low testosterone, which shows how central the pathway is.⁵ hCG's beta subunit carries extra sugar chains that slow its clearance, so a single injection acts for a day or more, much longer than natural LH. hCG raises testosterone inside the testis, but it does not supply follicle-stimulating hormone (FSH), the second pituitary signal that full sperm production also needs.

What the research shows on hCG

hCG's core effects are not in doubt. It has decades of clinical use and several FDA-approved indications. The open questions concern specific off-label uses, above all how well it protects fertility in men on testosterone.

The rationale for that use is solid. Exogenous testosterone suppresses gonadotropins, sharply lowers testosterone inside the testis and impairs sperm production.⁸ Recovery after stopping TRT is often slow and varies a great deal between men.⁸ A 2025 review lists hCG and FSH among therapies that may preserve or restore sperm production in selected men on TRT.⁸ The word "may" matters. Most supporting data come from small observational studies rather than large randomized trials, and protocols differ.

Men coming off anabolic steroids show a similar evidence gap. A 2014 review planned as a meta-analysis found no studies of high enough quality to pool. It fell back on expert opinion, which supports hCG, selective estrogen receptor modulators and careful use of testosterone.³

In adolescents with hypogonadotropic hypogonadism, hCG alone or combined with FSH is used to induce puberty in a way intended to protect future fertility. A recent review notes there is still no clear consensus on the best protocol.⁴

hCG also has a diagnostic role. Clinicians use hCG stimulation tests to assess testicular function in boys with conditions such as micropenis.¹

The weakest claim attached to hCG is weight loss. The "hCG diet" pairs small daily doses with a very low calorie diet. Controlled trials found the weight loss came from the calorie restriction, not the hormone, and FDA-approved labeling states that hCG has not been shown to be effective for obesity.

Studied for: Preservation of fertility and testicular volume on TRT, Hypogonadotropic hypogonadism, Ovulation induction.

hCG reference data

hCG dosage in published research

How hCG is used in practice

In fertility medicine hCG is a standard, well-understood drug. Reproductive endocrinologists use it to trigger ovulation. Urologists and endocrinologists use it, often with FSH or HMG, to restore sperm production in men with hypogonadotropic hypogonadism.

In men's health clinics, including telehealth services, it is usually prescribed off-label alongside testosterone and injected under the skin a few times a week. The dosing table on this page shows the ranges commonly used. Monitoring typically covers testosterone and estradiol, plus semen analysis for men planning a family.

Supply has been a recurring problem. In 2020 the FDA began regulating hCG as a biological product, which largely ended pharmacy compounding of it. Many clinics now use branded products, and some moved patients to gonadorelin or enclomiphene instead.

hCG is also sold on research-chemical and grey-market sites and is common in bodybuilding after steroid cycles. Those vials have no regulated quality control. A large glycoprotein depends on correct manufacture, storage and refrigeration to keep its potency, and buyers have no reliable way to check any of that. hCG is prohibited in male athletes under anti-doping rules.

hCG risks and side effects

Reported side effects include breast tenderness or gynecomastia, water retention, acne, mood changes and injection-site reactions. Many relate to estrogen. Stimulating the testes raises testosterone and also the testes' own estradiol output. Some clinicians add an aromatase inhibitor, but that brings its own risks, since estradiol that is pushed too low can affect bone, mood and libido.

hCG should not be used with hormone-sensitive cancers such as prostate or breast cancer, in precocious puberty or in pregnancy. In women having ovulation induction, the main serious risks are ovarian hyperstimulation syndrome and multiple pregnancy.

hCG also interferes with lab tests. It will produce a positive pregnancy test, and beta-hCG is a standard blood marker for testicular germ cell tumors.² A man taking hCG will have raised levels for reasons unrelated to cancer, so anyone using it should tell clinicians before blood work.

Long-term outcomes of years of combined hCG and TRT have not been well studied. Grey-market products add the risk of wrong dose, contamination or no active hormone at all.

Reported side effects

Alternatives to hCG

For men who want to protect fertility, the most direct option is to avoid testosterone while trying to conceive. A 2025 review states that exogenous testosterone is contraindicated in men trying to conceive, and notes that newer short-acting oral and nasal formulations may suppress the axis less.⁸

Clomiphene citrate, used off-label in men, and enclomiphene, which is not FDA approved, raise the body's own LH and FSH. Gonadorelin works one step higher, at the pituitary, but needs a responsive pituitary and has thinner evidence in TRT. When sperm counts stay low on hCG alone, clinicians add recombinant FSH or HMG (menotropins). For weight loss, FDA-approved options such as semaglutide and tirzepatide have strong trial evidence, unlike hCG.

Questions for a clinician

• What evidence applies to my situation, and at what level?
• What established alternatives should I consider first?
• What monitoring would be necessary, and how often?