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HCG (Human Chorionic Gonadotropin)19 residues (approx.)CPTMTRVLQGVLPALQVVCEach bubble = one amino acid. Size = residue mass. Color = chemical class.Uses closest standard amino acids for non-standard residues.Also known as: HCG, hCG, Pregnyl
Just 250 IU every other day kept intratesticular testosterone at 93% of baseline in the Coviello 2005 trial (n=29)[1]. HCG is a glycoprotein hormone that mimics luteinizing hormone, and it's become the standard tool for preserving testicular function on TRT. The FDA approved it decades ago under brand names Pregnyl, Novarel, and Ovidrel. One complication: compounding pharmacies lost the right to produce HCG in March 2020 after BPCIA reclassification, pushing costs from $20 to $289 or more per vial. Men on testosterone replacement still reach for it because nothing else matches the evidence for preventing atrophy and protecting fertility.
HCG (human chorionic gonadotropin, CAS 9002-61-3) is a 36.7 kDa glycoprotein produced naturally during pregnancy that binds the same receptor as LH on Leydig cells. Coviello and colleagues settled the dose question in 2005 [1]: at 250 IU every other day, intratesticular testosterone dropped only 7% from baseline; at 500 IU EOD, it climbed 26% above baseline. Without HCG, intratesticular testosterone fell to near zero. It binds the same receptor as LH on Leydig cells, triggering testosterone synthesis through the cAMP signaling cascade. Think of it as a long-acting LH substitute that bypasses the pituitary entirely. In practice, HCG sits at the center of two worlds. Fertility clinics use it under FDA-labeled indications for hypogonadotropic hypogonadism. TRT clinics prescribe it off-label to prevent testicular atrophy and maintain sperm production in men on exogenous testosterone. The community protocols at 250 to 500 IU every other day line up precisely with the published dose-response data. The regulatory situation changed sharply in March 2020. The FDA reclassified HCG as a biologic under the BPCIA, ending compounding pharmacy production overnight. Brand-name Pregnyl or Novarel now runs about $289 per 10,000 IU vial with a GoodRx coupon, up from $20 to $40 when compounded versions were available. That cost shift pushed many US telehealth clinics toward gonadorelin as a legal substitute, though no direct RCT proves gonadorelin matches HCG for intratesticular testosterone maintenance.
HCG binds to the LH/CG receptor (LHCGR) on Leydig cells in the testes. That receptor activation triggers the cAMP second messenger cascade, which drives cholesterol into the steroidogenic pathway and produces testosterone. The same receptor sits on Sertoli cells indirectly supporting spermatogenesis through paracrine signaling. What makes HCG useful during TRT is its ability to bypass the hypothalamic-pituitary axis completely. Exogenous testosterone shuts down the brain's GnRH pulse generator, which stops LH secretion. Leydig cells lose their signal, shrink, and stop producing testosterone locally. HCG replaces that missing LH signal at the gonadal level. The glycoprotein's molecular weight (36.7 kDa) gives it a half-life of roughly 33 hours, confirmed by the Pregnyl FDA label and Rizkallah's pharmacokinetic work. Endogenous LH has a half-life of about 20 minutes. That difference is why 250 to 500 IU every other day provides steady Leydig cell stimulation; you don't need continuous infusion or daily dosing. Subcutaneous bioavailability sits around 95%, clinically equivalent to intramuscular injection. Peak levels arrive at approximately 12 to 20 hours after subcutaneous administration. One limitation: HCG does not directly stimulate FSH receptors. Sertoli cell function depends on both testosterone (provided by HCG-stimulated Leydig cells) and FSH. In severe hypogonadotropic hypogonadism, HCG monotherapy produces sperm in about 78% of men, but adding exogenous FSH pushes outcomes higher (41 studies, n=1,673)[2].
Strong evidence that HCG maintains intratesticular testosterone (ITT) during exogenous testosterone use and preserves spermatogenesis. Dose-response established: 250 IU EOD maintains ITT at ~93% of baseline; 500 IU EOD brings ITT ~26% above baseline. HCG + FSH combination superior to HCG monotherapy for restoring spermatogenesis in severe hypogonadotropic hypogonadism. FDA-approved for fertility indications with decades of clinical data.
Coviello et al. 2005 (PMID 15713727): ITT dose-response in men on 200 mg/week testosterone enanthate; n=29. Confirmed: 250 IU EOD = -7% ITT vs baseline; 500 IU EOD = +26% ITT above baseline.
Most TRT-adjunct ITT data from small trials. No large RCT comparing HCG to gonadorelin for ITT maintenance in TRT patients. Long-term Leydig desensitization threshold (>1,500 IU/injection) based on animal data and clinical inference, not prospective human RCT.
Widely regarded as the gold standard for testicular preservation and fertility maintenance on TRT. Community protocols closely mirror clinical data. Cost and availability post-2020 BPCIA compounding ban are the dominant barriers; gonadorelin has largely replaced compounded HCG at US telehealth clinics.
Community protocols at 250-500 IU EOD precisely match the Coviello 2005 dose-response data. PCT protocols align with 2026 clinical cohort data (PMID 41147237). No significant divergence between science and community on dosing or indication.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 250 IU | EOD |
| Moderate | 500 IU | EOD |
| Aggressive | 1,000 IU | 3x/week |
Reconstitution math for a 5,000 IU vial with 2 mL bacteriostatic water: you get 2,500 IU per mL, or 250 IU per 10 units on a standard 100-unit insulin syringe. For 500 IU, draw to the 20-unit mark. For 1,500 IU (PCT dosing), that's 60 units. Always use bacteriostatic water, not sterile water. Multi-dose vials need the benzyl alcohol preservative. Sterile water accelerates degradation fast after reconstitution. Store reconstituted HCG refrigerated at 2 to 8 degrees Celsius and use within 60 days per the Pregnyl label. Lyophilized powder keeps at room temperature for up to 60 days or refrigerated for up to 2 years. The thing most beginners miss: brand-name HCG is the only legal option in the US since March 2020. If a telehealth clinic offers "compounded HCG," that product is federally illegal. GoodRx coupons bring Pregnyl 10,000 IU down to roughly $289 at major pharmacy chains. Check the NDC number on your vial to confirm it matches the Organon or Ferring product.
Typically used continuously alongside TRT, not cycled. For PCT, 2-4 weeks is common. Doses above 1,500 IU per injection risk Leydig cell desensitization.
For TRT adjunct use, HCG is administered continuously at doses ≤500 IU EOD to avoid Leydig cell LHCGR downregulation. Doses >1,500 IU per injection risk chronic receptor desensitization, reducing responsiveness over time. PCT use is inherently time-limited (2-4 months): the protocol self-terminates when spermatogenesis is restored. No formal "cycling on/off" schedule is indicated for continuous low-dose TRT adjunct use.
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Expected: Testicular volume maintained or improved. ITT preserved at ~93% of baseline vs near-zero suppression without HCG. Minimal E2 elevation at 250 IU for most men: AI often not required.
Monitor: Check estradiol (E2) at 4-6 weeks after starting. Many men do not need an AI at 250 IU EOD. No semen analysis required unless fertility is a goal.
Gather your supplies: HCG vial (5,000 IU or 10,000 IU), bacteriostatic water, a mixing syringe, and a 29 to 31 gauge insulin syringe (0.5 mL or 1 mL).
For a 5,000 IU vial, inject 2 mL of bacteriostatic water slowly down the side of the vial. Swirl gently until dissolved. Do not shake.
At 2,500 IU per mL concentration: 10 units on the syringe equals 250 IU; 20 units equals 500 IU; 60 units equals 1,500 IU.
Subcutaneous injection into abdominal fat is preferred by most TRT clinics. Pinch a fold of skin, insert the needle at a 45 to 90 degree angle, inject slowly, release the pinch.
Rotate injection sites across the abdomen, alternating sides. Thigh and upper arm are acceptable alternatives.
Date the vial on reconstitution day. Discard after 60 days.
Space injections evenly across the week (Monday, Wednesday, Friday works for 3x/week PCT protocols).
No dose adjustment: SC bioavailability ~95%, clinically equivalent to IM
More comfortable; easier to self-administer; less post-injection soreness. Abdominal fat, thigh, or upper arm acceptable sites. Tmax slightly delayed vs IM (~12 hours SC vs ~6 hours IM per Pregnyl label), not clinically relevant for EOD or 3x/week TRT dosing. Use 29-31G insulin syringe, 4-8mm needle.
Same dose as SC; no adjustment needed
FDA label specifies IM for all labeled indications. Tmax ~6 hours IM per Pregnyl label. More painful than SC. Deltoid or gluteal sites. More common in clinical fertility protocols; SC broadly substituted in TRT practice.
Post-2020 BPCIA ban, gonadorelin has largely replaced compounded HCG at US TRT clinics as the legal compoundable LH-stimulating alternative. Acts at pituitary level (vs HCG at gonadal level); stimulates both LH and FSH. Some clinics run both: brand-name HCG for proven ITT maintenance + gonadorelin to maintain pituitary axis stimulation.
Gonadorelin 100-200 mcg SC 2x/day (compounded) or pulsatile 50-100 mcg every 90 min (pump). Typically used as HCG substitute, not simultaneous addition.
Upstream HPG axis stimulator. Not a practical HCG alternative while on TRT: exogenous testosterone suppresses kisspeptin signaling at hypothalamic level, blunting efficacy. Potentially useful during post-TRT HPG axis recovery phase. Very limited human male data as of 2025; FDA PCAC nominated for TRT spermatogenesis indication (Oct 2024) but not yet approved for compounding.
Continuous GnRH agonist use causes LH/FSH suppression via pituitary receptor downregulation, directly opposing HCG's LH-mimetic effect on Leydig cells. Combination is physiologically counterproductive.
Do not combineBlocks pituitary GnRH receptors, suppressing endogenous LH/FSH. While HCG bypasses the pituitary, combining with GnRH antagonists creates unpredictable hormonal disruption without clear therapeutic rationale outside closely supervised fertility protocols.
Pricing updated 2026-04-09
Raised estradiol is the primary management challenge with HCG. The mechanism is straightforward: HCG stimulates Leydig cells to produce testosterone, and aromatase converts a portion of that testosterone to estradiol. Men with higher body fat or genetic aromatase polymorphisms are more susceptible. At 250 IU every other day, most men manage without an aromatase inhibitor. At 500 IU and above, symptomatic estradiol elevation becomes common enough that labs at 4 to 6 weeks are standard practice. Water retention and bloating follow from estradiol elevation and tend to appear at moderate to high doses. Gynecomastia risk exists if estrogen climbs unchecked, particularly in men already prone to breast tissue sensitivity. Nipple tenderness or puffiness warrants bloodwork, not panic. Leydig cell desensitization is the risk that gets less attention but matters most over time. Chronic dosing above 1,500 IU per injection can downregulate LHCGR expression on Leydig cells, reducing their responsiveness to both HCG and endogenous LH. This threshold comes from animal data and clinical inference rather than a prospective human RCT, but it's the reason every experienced protocol caps individual injections at 1,500 IU. Signs include declining testicular volume despite continued use and loss of the estradiol elevation you'd expect at a given dose. Injection site reactions are typical for both intramuscular and subcutaneous administration. Pain, redness, and mild swelling at the injection site affect a subset of users. Rotating sites and using 29 to 31 gauge insulin needles minimizes discomfort. Acne and oily skin show up in community reports at doses above 500 IU, consistent with the higher intratesticular testosterone production at those levels. Headache and irritability appear in clinical literature and user reports without a clear dose-response pattern. Not everyone responds to HCG for fertility. Some men remain azoospermic despite adequate dosing; HCG targets Leydig cells but doesn't directly stimulate Sertoli cells. FSH addition is the standard next step for non-responders [2]. When to stop or seek medical evaluation: persistent gynecomastia symptoms, hematocrit above 52%, signs of Leydig desensitization (declining response at stable dose), or any allergic reaction. Contraindicated in hormone-sensitive cancers (prostate, breast), precocious puberty, and pregnancy unless under direct fertility specialist supervision.
Verify HCG (Human Chorionic Gonadotropin) dosing and safety with a second opinion
Post-BPCIA reclassification (March 2020), compounded HCG is federally illegal in the US. Only FDA-regulated brand-name pharmaceuticals (Pregnyl by Organon, Novarel by Ferring, Ovidrel by EMD Serono) are legally available. Grey-market risk is low for domestic brand-name products. Risk exists for any "compounded HCG" offered by US telehealth platforms: these are illegal and may be mislabeled or counterfeit.
| Test | When | Target |
|---|---|---|
| Estradiol (E2): sensitive LC-MS/MS assay preferred | Baseline before starting HCG; repeat at 4-6 weeks; every 3 months ongoing | Symptomatic threshold varies by individual; many men tolerate up to 40-50 pg/mL; treat based on symptoms + labs, not labs alone |
| Total and free testosterone | Routine TRT monitoring schedule; baseline before HCG addition | — |
| Semen analysis | Baseline (if fertility is goal); at 3 months and 6 months on HCG | WHO 2021 reference: >16M/mL concentration, >42% motility, >4% normal morphology (Kruger strict) |
| LH and FSH | Baseline; primarily useful post-TRT during PCT to track HPG axis recovery. Not useful during active TRT (will be suppressed). | — |
| Hematocrit / CBC | Every 6 months on TRT + HCG | Hematocrit <52% (men) |
HCG stimulates Leydig cell testosterone production, which aromatizes to E2 via aromatase. E2 elevation is the most common management issue on HCG.
HCG may elevate total T above TRT target at higher doses: informs TRT dose adjustments.
Only objective measure of spermatogenesis response. Identifies non-responders requiring FSH addition.
Post-TRT, LH and FSH recovery confirms HPG axis normalization. Useful to time SERM tapering in PCT.
HCG-stimulated intratesticular testosterone production may contribute to erythrocytosis on top of TRT-driven erythropoiesis.
LH receptor activation begins. Intratesticular testosterone rises. Some men notice improved testicular fullness.
Testicular volume stabilizes or increases. Sperm parameters begin improving.
Full effect on intratesticular testosterone. Semen analysis may show improvement.
Spermatogenesis typically restored. Fertility potential significantly improved vs TRT-only.
Week 1 to 2: LH receptor activation and early ITT rise. HCG binds LHCGR on Leydig cells within hours. Intratesticular testosterone starts climbing within days. Many users report subjective testicular fullness in the first week; some notice improved mood or libido that could be ITT-driven or placebo. Mild injection site reactions are common. Estradiol elevation begins, check labs at week 4. Week 3 to 4: Testicular volume increases and sperm production begins responding to restored ITT levels. Atrophy visibly reverses for most men. Estradiol-related symptoms (water retention, nipple sensitivity) may appear in men with higher aromatase activity. Anastrozole or exemestane gets added based on lab confirmation at this stage. Week 6 to 8: ITT plateau reached for your dosing tier. Early semen analysis improvement is possible. Testicular size is subjectively "back to normal" for most users on community forums. Libido and sexual sensitivity hold steady. AI dosing typically stabilizes by this window. Acne may appear at higher doses (500 to 1,000 IU). Month 3 to 6: Spermatogenesis confirmed in the majority of men on 500 IU every other day. Hsieh 2013 [3] recorded 9 out of 26 pregnancies by month 6 on HCG plus TRT. Real-world 2025 cohort data [4] showed median sperm counts jumping from 18 million to 147 million, with an 84% improvement rate and 6 pregnancies during the study period. Non-responders with persistent azoospermia typically add FSH at this point. PCT Month 3 to 12: HPG axis normalization after anabolic steroid use. A 2026 cohort (n=79)[5] confirmed 87.5% normozoospermia at 12 months with HCG 1,500 IU 3x/week plus clomiphene, compared to 69.2% with clomiphene alone and 58.6% with no treatment. Testicular volume increased 20% or more in 70.8% of combined-therapy patients. Recovery runs slower after longer or heavier AAS cycles. Men who used concurrent HCG during their cycle recover faster in PCT.
HCG binds LHCGR on Leydig cells within hours of injection. ITT begins rising within days. cAMP cascade initiated; steroidogenesis increases.
Subjective testicular fullness reported within first week by many users. Some report improved mood or libido: possibly ITT-driven, possibly placebo.
Testicular volume measurably increases. Spermatogenesis begins responding to restored ITT levels. Scrotal fullness returns.
Testicular fullness consistently reported. Atrophy visibly reversing. E2-related symptoms (water retention, nipple sensitivity) may appear in men with higher aromatase activity.
ITT plateau reached per dosing tier. Early semen analysis improvement possible. Hsieh 2013 data: significant sperm parameter improvement measurable by month 3.
Testicular size subjectively "back to normal" for most. Libido and sexual sensitivity maintained. AI dosing typically stabilizes by week 6-8.
Spermatogenesis restored in majority on 500 IU EOD. Hsieh 2013 (PMID 23260550): 9/26 pregnancies by month 6 on HCG + TRT. Real-world 2025 cohort (PMID 40620361): median sperm count 18M → 147M; 84% improvement rate; 6 pregnancies during study.
Fertility success frequently reported at 3-6 month mark. Non-responders (azoospermia persisting) noted: prompts FSH addition discussion.
PMID 41147237 (2026): 87.5% normozoospermia at 12 months with HCG + SERM. PMID 38399562 (2024): ~96% spermatogenesis restoration within 12 months post-TRT with combined protocol. Testicular volume ≥20% increase in 70.8% of combined-therapy patients.
Recovery slower after longer or heavier AAS cycles. Men who ran concurrent HCG during cycle recover significantly faster in PCT. HCG blast before SERM-only PCT is common community practice.
Source: Pregnyl FDA label; confirmed by Rizkallah et al.
Loading the interactive decay curve.
HCG is FDA-approved under brand names Pregnyl (Organon), Novarel (Ferring), and Ovidrel (EMD Serono) for fertility indications including hypogonadotropic hypogonadism and ovulation induction. Off-label TRT adjunct use is legal when prescribed by a licensed physician. The critical regulatory change happened on March 23, 2020. The FDA reclassified HCG from a drug to a biologic under the Biologics Price Competition and Innovation Act (BPCIA). Compounding pharmacies lost the authority to produce HCG on that date. Any US-sourced "compounded HCG" sold after March 2020 is federally illegal and may be mislabeled or counterfeit. Only brand-name pharmaceutical HCG dispensed by licensed US pharmacies is legal. International personal importation (Canada, Mexico) exists in a legal grey area, with cold chain and quality verification concerns. HCG is banned by the World Anti-Doping Agency (WADA) at all times for male athletes under the S2 category (peptide hormones, growth factors, and related substances). A positive test results in a sanction. This content is for educational purposes only and does not constitute medical advice. Consult a licensed healthcare provider before using any prescription medication.
Peptide Schedule Research TeamReviewed Apr 20268 Citations
