The best-supported peptides for testosterone come down to one: hCG, an FDA-approved hormone that acts like LH and tells the testes to make testosterone. It is approved for men with low testosterone caused by a pituitary or hypothalamic problem, and in a 2025 meta-analysis 78% of such men produced sperm on gonadotropin treatment.[3][4] Gonadorelin has no approved human product in the US, and kisspeptin-10 is experimental: both raise testosterone briefly in small studies, with no long-term trials.[8][10]
Testosterone replacement therapy (TRT) itself remains the most-studied treatment for confirmed low testosterone. This guide compares the three peptides with TRT and explains who might consider each. For more, see our sexual health peptides hub.
Evidence-graded table
| Peptide or drug | Evidence level | What was shown | FDA status | Our profile |
|---|---|---|---|---|
| Testosterone (TRT) | FDA-approved for this use | No excess major heart events vs placebo in 5,246 men (TRAVERSE)[14] | Approved; Schedule III | Peptides vs TRT |
| hCG | FDA-approved for this use | Restores testosterone and sperm in pituitary-type hypogonadism[4] | Approved: hypogonadotropic hypogonadism in males[3] | hCG |
| hCG added to TRT | Small human studies | Kept semen quality stable in 26 men over about a year[6] | Off-label use | hCG |
| Gonadorelin (pump) | Small human studies | Pulses every 2 hours induced puberty in men with GnRH deficiency[9] | Human products discontinued[8] | Gonadorelin |
| Gonadorelin (daily injections with TRT) | No evidence, marketing only | No published trials | Compounded only | Gonadorelin |
| Kisspeptin-10 | Small human studies | Raised LH and testosterone for hours to days[10][12] | Not approved; FDA safety-risk list[13] | Kisspeptin-10 |
How these peptides work
Testosterone production runs on a chain of signals:
- The hypothalamus releases kisspeptin, which triggers GnRH.
- GnRH (synthetic version: gonadorelin) tells the pituitary to release LH and FSH.
- LH tells the testes to make testosterone; FSH and testosterone inside the testes drive sperm production.
Each peptide acts at one link. hCG copies LH (step 3), gonadorelin copies GnRH (step 2), and kisspeptin acts at the top (step 1). That is why these options only work when the testes are healthy. If the problem is in the testes themselves, called primary hypogonadism, testosterone therapy is the usual choice.[1]
Diagnosis comes first
Guidelines agree that low testosterone should be diagnosed with symptoms plus at least two early-morning blood tests showing low levels, then a look for the cause.[1][2] LH and FSH results separate primary from secondary hypogonadism. That split decides which of the options below can work.
TRT: the most-studied option, with a fertility cost
Testosterone gels and injections raise levels directly. In TRAVERSE, testosterone gel did not increase heart attacks, strokes or cardiovascular deaths versus placebo in men aged 45 to 80 at high heart risk.[14] In February 2025 FDA added the TRAVERSE results to testosterone labels, removed the boxed warning about heart risk and added a blood pressure warning.[15]
The trade-off: outside testosterone switches off LH and FSH, so the testes shrink and sperm counts usually fall. The AUA guideline says men who want to keep their fertility should not be given testosterone, and it describes non-testosterone options for them, including hCG and oral medicines such as selective estrogen receptor modulators and aromatase inhibitors.[2]
hCG: the approved peptide
hCG is approved for hypogonadotropic hypogonadism in men, as well as prepubertal undescended testes and ovulation induction in women.[3] In a 2025 meta-analysis of 41 studies and 1,673 men with this condition, 78% produced sperm after a median of 18 months on gonadotropins, and adding FSH to hCG worked better than hCG alone.[4]
With TRT. In a small randomized study of healthy men on weekly testosterone, hCG doses of 250 to 500 IU every other day kept testosterone inside the testes near normal levels.[5] In a chart review of 26 men on TRT plus 500 IU hCG every other day, semen quality did not change over about a year.[6] These are small studies, not large trials.
Since March 23, 2020, hCG is regulated as a biologic, and FDA has said such products are no longer eligible for the usual compounding exemptions.[7] That shift is one reason some clinics began offering gonadorelin instead.
Gonadorelin: real science, unproven use
FDA approved two human gonadorelin products, but Drugs@FDA lists both as discontinued.[8] Natural GnRH is released in pulses about every 1 to 2 hours. In the 1980s, researchers used small pumps delivering a dose every 2 hours to induce puberty in men with GnRH deficiency.[9]
Today, gonadorelin is compounded and often given as one or two injections a day to men on TRT. No published trial has tested whether that schedule keeps the testes working. Continuous, non-pulsed GnRH exposure can actually suppress the pituitary, which is how GnRH-agonist drugs for prostate cancer work; in a classic monkey study, continuous GnRH shut down LH and FSH release while pulses restored it.[17] Read more in our peptides for male fertility guide.
Kisspeptin: promising research, not a treatment
Kisspeptin-10 raised LH within 30 minutes in healthy men, and a 22.5-hour infusion raised testosterone from 16.6 to 24.0 nmol/L.[10] It also raised testosterone in men with type 2 diabetes and mildly low levels.[11] A 2026 study found daily 8-hour under-the-skin infusions kept LH elevated for 12 days, though continuous infusion for 5 days lost its effect on LH.[12]
These studies used hospital infusions in small groups. None tested symptoms, fertility or safety over months. FDA lists kisspeptin-10 among compounding substances that may present significant safety risks.[13]
Which option fits? Questions for your clinician
- Is my low testosterone primary (testes) or secondary (pituitary or hypothalamus)?
- Do I want children in the next few years? If so, is hCG, with or without FSH, a better fit than TRT?
- If I am already on TRT, what evidence supports adding hCG or gonadorelin, and how will we check sperm and testicular size?
- What monitoring will I need: hematocrit, blood pressure, PSA, estradiol?
Also compare erectile dysfunction options in PT-141 vs Viagra and prostate topics in peptides for prostate health.
