HCG
Also called human chorionic gonadotropin, Pregnyl, Ovidrel
HCG mimics LH - the natural signal that tells the testes to keep making testosterone and sperm.
This one has been through full clinical trials and is an approved medicine somewhere in the world. The ranges below are drawn from those trials and from what the community reports using.
- Hormone balance
- Sexual health
The quick answer
HCG mimics LH - the natural signal that tells the testes to keep making testosterone and sperm. On TRT, testosterone alone tends to shut that system down, so HCG is added to keep everything switched on: natural production, fertility, testicular size, and drive.
Worth saying up front: HCG is an actual prescription medication, and the right home for it is under a licensed prescriber who can dose and monitor it - including keeping an eye on estrogen, which can rise alongside testosterone. Used sensibly as a TRT companion it's typically a small dose two or three times a week. This is the one "peptide" here that's really a regulated drug, so regard the guidance as educational.
Why people use it
💪 Keeps natural testosterone flowing on TRT; 👶 Preserves fertility; ⚖️ Prevents testicular shrinkage; ❤️ Supports libido and mood; 🔄 Restores the full hormone cascade
What people report using
These are ranges other people have reported running. They are here so you can see what has actually been done — they are not medical advice and not a recommendation for you.
- How often
- Mon / Wed / Fri
- Route
- subcutaneous
- Evidence for this
- Large human trials
10,000 IU vial + 2ml BAC water = 5,000 IU/ml. 250 IU = 5u; 500 IU = 10u. House protocol: 500 IU (10 units), three times a week, under the skin.
Work out your own units on the reconstitution calculator — the most common serious mistake in this area is arithmetic, not chemistry.
What to expect, and when
- First thing people notice
- Weeks 1–2 (libido)
- When it gets real
- Weeks 2–4 (testicular function)
- Where it peaks
- Months 2–3 (fertility)
- Patience needed
- Medium - fertility takes longer
- Days 3–7Leydig cells stimulating · testosterone production beginning
HCG begins stimulating Leydig cells within days of the first injection. Intratesticular testosterone production restarts. The testes begin responding to the LH signal - this is the foundational effect that everything else depends on.
- Weeks 1–2Libido improvement · mood lift
About 80% of men report a libido boost within 1–2 weeks of adding HCG to a TRT protocol. LH receptors in the brain contribute to improved mood and sexual drive independently of the hormonal effect. This is often the first felt signal that HCG is working.
- Weeks 2–4Testicular volume maintained · sperm production resuming
Testicular atrophy from TRT is meaningfully countered. Sperm production restarts - clinical data shows normal sperm motility increasing from 5% to 58% with HCG co-administration. If fertility is the goal, sperm quality improvements take 2–3 months to show in semen analysis (reflecting the full sperm maturation cycle).
- Months 2–3Full fertility markers restored · complete hormonal cascade
Semen analysis at 2–3 months reflects the full restoration of sperm production. Pregnenolone and progesterone (upstream hormonal precursors suppressed by TRT) are also maintained by HCG, restoring the complete steroid hormone cascade - not just testosterone.
💡 HCG is a preventative compound as much as a restorative one - the time to start is when you begin TRT, not after atrophy has occurred. Restoring testicular function after significant atrophy takes longer than maintaining it from the start. Early introduction produces better long-term outcomes.
Side effects, and what people do about them
A quick heads-up on this one: it's a prescription medication, so it's best run alongside a doctor with simple bloodwork - which also makes it easy to keep everything dialled in. Because it switches your natural hormones back on, some people notice a little acne, mood shifts, or water retention early on. Kept at sensible doses with a prescriber, most men use it very comfortably.
Go deeper
Open these only if you want them.
How it actually works
Glycoprotein hormone that binds the LH/choriogonadotropin receptor. In men that drives Leydig cells to make testosterone; in women it triggers ovulation. It is a hormone acting on a hormone receptor rather than a signalling peptide, which is why its effects are larger and less subtle than most of what sits near it.
For stacking, the important relationship is with kisspeptin. Kisspeptin acts one level higher up - it drives GnRH release, which drives the pituitary to make LH and FSH. HCG skips that chain and mimics LH directly. Running both is asking the same axis for the same thing twice by two different doors.
What people report, in full
Among men on TRT, HCG is considered essential rather than optional - around 95% see it as necessary to preserve fertility and testicular size, with only a small minority skipping it over cost. It acts fast (it mimics LH within hours), testicular volume tends to recover within a week or two, and sperm production comes back more slowly. For men using it specifically to restore fertility, results are more variable and depend on where they're starting from. One thing the community consistently flags: because HCG can raise estrogen, keeping an eye on your estradiol is part of using it properly.
Sources and review
https://pubmed.ncbi.nlm.nih.gov/19066302/
https://pubmed.ncbi.nlm.nih.gov/9758439/
Last reviewed 2026-09-06.
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