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How hCG Works: Mechanism and Pharmacology

How hCG works: its target and mechanism as the sources state them, how long it acts, and what is still unknown.

Medical review pendingGonadotropinUpdated
Class
Gonadotropin
FDA status
Approved (prescription only)
Routes studied
injection; subcutaneous self-injection; intramuscular hCG/hMG
Half-life
pooled half-life 5.8 days
injection (urinary and recombinant hCG), in people · Clinical endocrinology 2024, PMID 38446525

How long it acts

Half-life values from FDA labels and published studies, by route. Animal values are labelled and do not describe people.

hCG half-life by route
RouteHalf-lifeMeasured inSource
injection (urinary and recombinant hCG)pooled half-life 5.8 daysPeopleClinical endocrinology 2024, PMID 38446525

Full detail, including drug-testing windows, is on the hCG half-life page.

What hCG mimics

The Novarel label describes hCG as a placental hormone made of an alpha and a beta subunit.[2]

Its alpha subunit is essentially identical to those of LH, FSH and TSH.[3]

hCG can stand in for LH at the mid-cycle surge that triggers ovulation.[2]

What happens in the body

In the testis the labels say hCG stimulates Leydig cells to make androgens, and in the ovary it stimulates the corpus luteum to make progesterone.[2]

In gonadotrophin-deficient men on repeated dosing, serum testosterone stayed stable after injection and did not differ between urinary and recombinant hCG.[1]

A trial comparing pulsatile GnRH infusion with hCG/hMG injections in hypogonadotropic men found GnRH led to earlier sperm production.[4]

Why the injections are spaced

In the multi-dose study the pooled half-life of both hCG products was 5.8 days.[1]

The Novarel label's regimen for hypogonadotropic hypogonadism repeats injections three times a week, then twice a week.[2]

What is not shown

The cached sources for this page contain 0 Mechanism of Action sections from a product label, because the labels use a Clinical Pharmacology heading instead, and 5 mechanism-relevant abstracts.

Calculated from label mechanism sections 0; mechanism abstracts 5. Formula: count of cached items with the stated content

Related peptides

hCG vs EnclomipheneSERM (not a peptide)hCG vs HGHRecombinant growth hormone

Common questions

How long does hCG act in the body?

The half-life values we found are pooled half-life 5.8 days (injection (urinary and recombinant hCG)). A half-life is how long the amount in the body takes to fall by half; it is not the same as how long an effect lasts.

How does hCG work?

By acting like LH: the Pregnyl label says its action is virtually identical to that of pituitary LH.[3]

More on hCG

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.BenefitsClaimed benefits next to what published studies measured.

Sources

  1. 1Single and multi-dose pharmacology of recombinant and urinary human chorionic gonadotrophin in men.Clinical endocrinology · 2024PMID 38446525Accessed 2 Oct 2026
  2. 2NOVAREL ® (chorionic gonadotropin) for injection, for intramuscular use Initial U.S. Approval: 1974FDA label, DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
  3. 3Pregnyl ® (chorionic gonadotropin) for injectionFDA label, DailyMed · current labeldailymed.nlm.nih.govAccessed 2 Oct 2026
  4. 4Optimal treatment for spermatogenesis in male patients with hypogonadotropic hypogonadism.Medicine · 2019PMID 31374027Accessed 2 Oct 2026

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