library.onepin.app/hcg Peptide Education Library

Education only, not medical advice◆ 21+◆ Every dose is an example to finalize with a licensed provider

OnePin Peptide Library · Hormonal

Hormonal Glycoprotein hormone (37 kDa) Controlled substance Prescription drug

HCG

Human Chorionic Gonadotropin · Pregnyl

Glycoprotein hormone (37 kDa)LH receptor agonistFDA-approved medicationGonadotropin

Human Chorionic Gonadotropin (HCG) is a naturally occurring glycoprotein hormone (~37 kDa) composed of two subunits (alpha and beta). The alpha subunit is shared with LH, FSH, and TSH; the beta subunit confers biological specificity. HCG mimics luteinizing hormone (LH) by binding to LH/CG receptors on Leydig cells in the testes, stimulating intratesticular testosterone production and preventing testicular atrophy during exogenous testosterone replacement therapy (TRT). It is FDA-approved for hypogonadism and certain fertility indications. HCG is essential in TRT protocols to maintain testicular function, fertility potential, and intratesticular hormonal milieu.

Quick Start

Route

SubQ or IM injection

Start low

250-500 IU per injection

Frequency

2-3 times per week

Timing

No fasting requirement

SubQ or IM. Consistent timing. Often every other day or 2-3x per week. Pin alone.

❋

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Quick Start

Conservative start

250-500 IU per injection · SubQ or IM injection · 2-3 times per week

Lowest starting point. Hold about a week to assess tolerance before stepping up.

250-500 IU per injection

2-3 times per week

Standard

TRT Testicular Preservation

250-500 IU · SubQ · 2x Weekly

human clinical trial · Coviello et al. 2005 (J Clin Endocrinol Metab)

250-500 IU

2x Weekly

Intermediate

PCT / Fertility Monotherapy

1000-1500 IU · SubQ · 3x Weekly

human clinical trial · FDA Pregnyl label

1000-1500 IU

3x Weekly

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How it works

HCG binds to LH/CG receptors on Leydig cells, activating cAMP/PKA signaling to stimulate steroidogenesis (testosterone, estradiol, progesterone, DHEA synthesis within the testes). This maintains intratesticular testosterone (ITT) concentrations, which are 50-100x higher than serum levels and essential for spermatogenesis. During TRT, exogenous testosterone suppresses pituitary LH secretion via negative feedback, causing Leydig cell inactivity and testicular atrophy. HCG replaces the missing LH signal, keeping Leydig cells active and testes at normal volume. HCG also stimulates aromatase activity in Leydig cells, which means estradiol production increases alongside testosterone.

What to expect

Early

Days 1–7

Days 1-14: Testicular response begins. ITT levels start to recover if previously suppressed.

Mid

Weeks 2–4

Weeks 2-8: Testicular volume stabilizes or recovers. Estradiol levels may rise (monitor).

Later

Weeks 4–12

Ongoing: Continuous use alongside TRT. Monitor via labs (total T, free T, estradiol, LH, FSH, semen analysis if fertility relevant).

Evidence

HumanStrong

AnimalPresent

In-vitroPresent

2013Concomitant intramuscular human chorionic gonadotropin preserves spermatogenesis in men undergoing testosterone replacement therapy · Hsieh TC, Pastuszak AW, Hwang K, Lipshultz LI, Journal of Urology ↗peer reviewed

2019Human Chorionic Gonadotropin monotherapy for the treatment of hypogonadal symptoms in men with total testosterone > 300 ng/dL · La Vignera S, Condorelli RA, Cimino L, et al, International Journal of Impotence Research ↗peer reviewed

2022Efficacy and Safety of Human Chorionic Gonadotropin Monotherapy for Men With Hypogonadal Symptoms and Normal Testosterone · Lo EM, Rodriguez KM, Pastuszak AW, Khera M, Journal of Urology ↗peer reviewed

2009A combined analysis of data to identify predictive factors for spermatogenesis in men with hypogonadotropic hypogonadism treated with recombinant human follicle-stimulating hormone and human chorionic gonadotropin · Warne DW, Decosterd G, Okada H, Yano Y, Koide N, Howles CM, Fertility and Sterility ↗peer reviewed

The honest take

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Testicular preservation during TRT

Well-established medical indication. Standard of care recommendation in TRT protocols.

Fertility preservation

FDA-approved for this purpose. Maintains spermatogenesis during exogenous testosterone use.

Weight loss (HCG diet)

Not supported

The HCG diet is not supported by evidence. FDA has warned against OTC HCG weight loss products. Any weight loss is from the 500-calorie diet, not HCG.

Interactions & stacking

What's safe to combine, and what belongs in a separate pin.

Safe & synergistic

AnastrozoleAI manages estrogen from HCG-stimulated testosterone production.

BPC-157No direct interaction. Separate injection sites and syringes.

Testosterone CypionateHCG maintains testicular function, size, and fertility during TRT. Most common TRT adjunct.

EnclomipheneBoth support HPG axis from different angles. HCG mimics LH, enclomiphene blocks estrogen feedback.

Keep separate

ALL (syringe)Large glycoprotein (37 kDa). Always pin alone in separate syringe. Different molecular class from peptides.

Side effects & safety

Commonly reported

Estradiol elevation (aromatase stimulation)
Water retention
Injection site irritation
Mood changes related to E2 fluctuation

Less common & notes

Gynecomastia if E2 is uncontrolled.
Testicular discomfort at higher doses.
Very rare: OHSS (ovarian hyperstimulation, relevant only in female fertility use).
Anti-HCG antibodies possible with long-term use but clinically rare.

Pharmacokinetics

Illustrative plasma concentration · 24 h

Half-life

33h

Peak · Tmax

Elimination

165h

Activity

48-72 hours

Storage. BAC water reconstitution: 30-60 days refrigerated at 2-8C. Sterile water reconstitution: 24-48 hours only. BAC water is essential for multi-dose vials. Unreconstituted vials stable at room temperature or refrigerated per manufacturer. Protect from light.

Regulatory status

FDA-approved for hypogonadism, cryptorchidism, and certain fertility indications. Prescription required. WADA prohibited under S2. Compounded versions available. Schedule III in some contexts.

Put it to work

Calculate, log & track

Open HCG straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.

Open HCG in the app →

Go deeper

The guide & community

The complete HCG walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.

Join the community ↗

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