Side-by-side · Research reference

GHRP-6vsHCG

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 1HUMAN-REVIEWED10/36 cited

BFDA-ApprovedHUMAN-REVIEWED12/52 cited

GHRP-6

Hexapeptide GHRP · Strong appetite stimulant

100–200 mcgPer doseBowers 1990

Phase 1Evidence levelBowers 1990

~15 minHalf-lifeMalagón 1999

SQ · Multiple sites · 1–3×/day

HCG

Glycoprotein Hormone · LH Mimetic

2,000 IUTypical dose (2×/wk)Konsam 2026 Zachariou 2026

70–90%Sperm induction rateHuijben 2026 Zachariou 2026

12–24 moTime to sperm appearanceHuijben 2026 Nariyoshi 2025

IM or SQ · 2–3×/week

01Mechanism of Action

Parameter

GHRP-6

HCG

Primary target

Ghrelin receptor (GHS-R1a)Bowers 1990

LH receptors on testicular Leydig cellsSchröder-Lange 2025

Pathway

GHS-R1a → Gαq → Ca²⁺ → GH release; central appetite driveBowers 2002

hCG → Leydig cell LH receptor → Intracellular cAMP → Steroidogenesis pathway activation → Testosterone synthesis

Downstream effect

GH pulse + strong appetite stimulation; modest IGF-1 elevationBowers 2002

Elevated intratesticular testosterone, restored spermatogenesis, virilization, secondary sex characteristic developmentKonsam 2026 Zachariou 2026

Feedback intact?

—

No — exogenous hCG bypasses hypothalamic-pituitary axis; endogenous LH remains suppressed

Origin

Synthetic hexapeptide; first-generation GHRP from Bowers groupBowers 1990

Heterodimeric glycoprotein (alpha subunit shared with LH/FSH/TSH; beta subunit confers specificity). Available as urinary-derived or recombinant formulations.

Antibody development

—

Rare with recombinant; possible with urinary-derived formulations

02Dosage Protocols

Parameter

GHRP-6

HCG

Standard dose

100–200 mcg per injectionBowers 1990

—

Frequency

1–3× per day

—

Lower / starter dose

50 mcg per dose

—

Evidence basis

Phase 1 + clinical practiceBowers 1990

RCT / Meta-analysis / FDA-approvedKonsam 2026 Huijben 2026

Duration

8–12 weeks on / 4 off

—

Reconstitution

Bacteriostatic water

—

Timing

Pre-meal preferred for appetite support

—

Half-life

~15 minMalagón 1999

—

Hypogonadotropic hypogonadism (monotherapy)

—

2,000 IU IM/SQ 2–3×/weekKonsam 2026 Zachariou 2026

Titrate to normalize testosterone (300–1,000 ng/dL) or achieve target AMH ~7.4 ng/mL.

Combined therapy (hCG + FSH)

—

hCG 2,000 IU 2×/wk + rFSH 75 IU 3×/wkKonsam 2026 Nariyoshi 2025

Preferred for azoospermia; FSH added after initial hCG phase or from outset.

Triple therapy (experimental)

—

hCG 2,000 IU 2×/wk + rFSH 75 IU 3×/wk + testosterone 100 mg IM q2wkKonsam 2026

May accelerate virilization; reduces hCG requirements (~30% lower cumulative dose vs monotherapy).

Cryptorchidism (pediatric)

—

500–4,000 IU IM 2–3×/week for 3–6 weeks

Duration to sperm appearance

—

12–24 months (median ~18 mo)Huijben 2026 Zachariou 2026

Congenital HH may require longer treatment; acquired HH responds faster.

Route

—

Intramuscular or subcutaneousKonsam 2026

Monitoring

—

Serum testosterone, semen analysis q3–6mo, testicular ultrasound

Thickened seminiferous tubules (>300 μm) on ultrasound predict imminent sperm appearance.Nariyoshi 2025

04Side Effects & Safety

Parameter

GHRP-6

HCG

Hunger

Pronounced — defining feature vs ipamorelin

—

Cortisol elevation

Mild

—

Prolactin elevation

Mild

—

Injection site reaction

Mild

Pain, erythema (mild, transient)

Cancer risk

Contraindicated in active malignancy

—

Pregnancy / OB

Avoid

—

Gynecomastia

—

Aromatization of elevated testosterone to estradiol; dose-dependent

Testicular discomfort / Edema

—

Rapid testicular growth in hypogonadal males; usually self-limiting

Polycythemia

—

Elevated hematocrit from supraphysiological testosterone; monitor CBC

Mood / Libido changes

—

Variable; usually positive with normalization of testosterone

Acne / Oily skin

—

Androgen-mediated; dose-dependent

Prostate concerns

—

Monitor PSA in older males; hCG restores physiological testosterone (not supraphysiological)

Antibody formation

—

Rare with recombinant; possible with urinary-derived

Absolute Contraindications

GHRP-6

·Active malignancy
·Pregnancy / breastfeeding

HCG

·Androgen-dependent malignancy (prostate, breast cancer)
·Hypersensitivity to hCG or excipients
·Precocious puberty

Relative Contraindications

GHRP-6

·Severe insulin resistance (appetite-driven caloric load)

HCG

·Untreated obstructive sleep apnea
·Severe cardiovascular disease (polycythemia risk)
·History of thromboembolism

05Administration Protocol

Parameter

GHRP-6

HCG

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.

Add sterile water or bacteriostatic water per manufacturer instructions. Typically 1–2 mL per 5,000–10,000 IU vial. Roll gently — do not shake. Solution should be clear.

2. Injection site

SQ — abdomen. Rotate sites.

Intramuscular: ventrogluteal, vastus lateralis, or deltoid. Subcutaneous: abdomen, avoiding navel (2-inch radius). Rotate sites to prevent lipohypertrophy.

3. Timing

Pre-meal for appetite support; pre-sleep for GH alignment.

Administer 2–3 times per week. Consistent weekly schedule recommended (e.g., Monday/Thursday or Monday/Wednesday/Friday).

4. Storage

Lyophilised: room temp. Reconstituted: refrigerate ≤30 days.

Lyophilized: room temperature, light-protected. Reconstituted: refrigerate 2–8 °C. Bacteriostatic water extends shelf life to ~30 days; sterile water use within 72 hours.

5. Needle

29–31G, 4–8 mm insulin syringe.

IM: 21–23G, 1–1.5 inch. SQ: 25–27G, 5/8 inch. Inject slowly (30–60 seconds for IM).