Library / Peptides / Hormone Optimization / HCG

Strong evidence · Grade A

HCG

HCG (Human Chorionic Gonadotropin)

Score

82 / 100

Class

Hormone Optimization

Brand

Pregnyl

Status

Strong Evidence

TL;DR

Part 01 · How it works

Mechanism.

Human chorionic gonadotropin (HCG) is a glycoprotein hormone naturally produced by the placenta during pregnancy. Structurally, it shares a common alpha subunit with LH, FSH, and TSH, and its beta subunit gives it LH-like biological activity. In clinical medicine, HCG is FDA-approved for the treatment of female infertility (to trigger ovulation), male hypogonadism, and cryptorchidism. It is widely used off-label alongside testosterone replacement therapy to maintain testicular function and fertility.

When you take testosterone replacement, your brain stops sending the signal (LH) to your testes to produce testosterone on their own — so they shrink and stop making sperm. HCG is like a substitute signal that keeps the factory running even when headquarters has gone quiet.

Mechanism · technical

HCG mimics luteinizing hormone (LH) by binding to the LH/CG receptor on Leydig cells in the testes, stimulating intratesticular testosterone production and maintaining spermatogenesis. In women, it mimics the LH surge to trigger final oocyte maturation and ovulation in assisted reproduction protocols. Because exogenous testosterone suppresses LH via negative feedback, co-administration of HCG preserves testicular size, endogenous testosterone production, and fertility during TRT.

Part 02 · Dosing & administration

How it's taken.

Values below describe how HCG has been administered in published trials and labeling. Provided for educational purposes only — this is not medical advice and not instructions for self-administration. Consult your healthcare provider before making any health decision.

Standard dose

250-500 IU for TRT adjunct; 5000-10000 IU for fertility protocols

Subcutaneous or Intramuscular injection · 2-3x weekly (TRT adjunct); varies for fertility

Duration

Ongoing while on TRT or per fertility protocol

FDA-approved for hypogonadism and fertility. Commonly used off-label as TRT adjunct to maintain testicular function and fertility. Dosing varies widely by indication.

Need help with reconstitution?

Use the free peptide calculator for dilution, unit conversion, and injection volume.

Open calculator

Part 03 · Safety

Side effects, rare serious events, who shouldn't.

Reported side effects

Side effects include headache, irritability, water retention, and gynecomastia due to increased estradiol conversion from elevated intratesticular testosterone. Injection site pain is common. In women undergoing fertility treatment, ovarian hyperstimulation syndrome (OHSS) is a significant risk. Rare side effects include blood clots and allergic reactions.

Absolute · do not use

Hormone-sensitive cancers (breast, prostate, ovarian)

Precocious puberty

Pregnancy (except under specific obstetric protocols)

Known hypersensitivity to HCG or any component

Undiagnosed uterine bleeding

Ovarian cysts or enlargement not due to PCOS

Primary hypogonadism (will not respond to HCG stimulation)

Interactions

Testosterone replacement therapy

HCG stimulates endogenous testosterone; concurrent exogenous testosterone may cause supraphysiologic levels

Moderate

Aromatase inhibitors (anastrozole)

HCG increases testosterone which aromatizes to estrogen; AI may be needed to manage estrogen levels

Moderate

Clomiphene citrate

Both stimulate gonadal function; additive effect on testosterone and estrogen levels

Moderate

Anticoagulants

HCG may increase thromboembolic risk; monitor coagulation parameters

Moderate

Labs to monitor

Total and Free Testosterone

Baseline, 4 weeks, then every 3 months

HCG stimulates testicular testosterone production

Estradiol (E2)

Baseline and monthly

HCG increases aromatization and estrogen

Beta-hCG Level

As needed

Confirm appropriate dosing and response

CBC with Differential

Baseline and every 3 months

Testosterone elevation can increase hematocrit

CMP (Comprehensive Metabolic Panel)

Baseline and every 3 months

Liver and kidney function

Semen Analysis

Baseline and at 3 months

If used for fertility preservation

Part 04 · Evidence

How strong is the evidence?

Scores derived from rating, indexed studies, regulatory status, and catalogued safety data for this peptide. Curated per-peptide scoring replaces this when available.

Grade B

Grade B. Evidence is strongest where indications match regulatory approval — pair with a clinician when applying beyond label.

Clinical efficacy

Rating reflects consistent peer-reviewed evidence in its indication.

Study quality

2 indexed studies in our dataset. Designs vary — see Research log for per-study grades.

Regulatory clarity

FDA-approved for at least one indication.

Safety profile

Based on 7 documented contraindications, 4 interactions, 6 lab checkpoints.

Long-term data

Years of post-approval surveillance available.

Part 05 · Research log

Every study we cite.

Each study with its published finding and a plain-language note on limitations or funding.

2005

HCG maintains intratesticular testosterone in men on testosterone therapy

Low-dose HCG (250 IU EOD) maintained intratesticular testosterone levels during exogenous testosterone use

Small but well-designed crossover study

PMID 15713727 ↗

2019

HCG for male infertility and hypogonadism

HCG effectively stimulated spermatogenesis and testosterone production in hypogonadal men

Review of clinical evidence; well-established indication

Part 06 · Cost & access

Where you can get it.

Regulatory status

HCG is FDA-approved for female infertility, male hypogonadism, and prepubertal cryptorchidism. Brand names include Pregnyl, Novarel, and Ovidrel (recombinant choriogonadotropin alfa). As of 2020, the FDA reclassified HCG as a biologic under the BPCIA, which affected compounding pharmacy availability. Some compounding pharmacies continue to provide it under specific regulatory pathways.

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Part 07 · Your appointment

Questions to bring.

Should I use HCG concurrently with TRT or is it unnecessary for my situation?

What dose and frequency of HCG is appropriate to maintain fertility?

How will HCG affect my estradiol levels, and should I monitor for estrogen-related side effects?

What labs should I track while on HCG (testosterone, estradiol, LH, FSH, semen analysis)?

Is recombinant HCG preferable to urinary-derived HCG?

Are there alternatives to HCG for maintaining fertility on TRT, like enclomiphene?