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Best Peptides for Low Testosterone — Research Evidence Comparison
CJC-1295 + Ipamorelin GHRH analogue + ghrelin agonist. Stimulates pulsatile GH release, elevates IGF-1, upregulates Leydig cell steroidogenesis 12–16% increase in total testosterone; 16–20% increase in free testosterone (16-week trials) 2–3× weekly subcutaneou
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- CJC-1295 + Ipamorelin
- GHRH analogue + ghrelin agonist. Stimulates pulsatile GH release, elevates IGF-1, upregulates Leydig cell steroidogenesis
- 12–16% increase in total testosterone; 16–20% increase in free testosterone (16-week trials)
- 2–3× weekly subcutaneous injection
- Yes. LH and FSH remain at baseline
- Strongest evidence for indirect testosterone support; preserves natural production
- Hexarelin
- Potent ghrelin receptor agonist. Acute GH spike, higher cortisol co-release risk
- 10–14% testosterone increase; diminishes after 12 weeks due to receptor desensitisation
- Daily or every-other-day injection
- Yes. But prolonged use can suppress GH responsiveness
- Effective short-term; not sustainable beyond 8–12 weeks
- MK-677 (Ibutamoren)
- Non-peptide ghrelin mimetic. Oral bioavailability, sustained GH elevation without tachyphylaxis
- 8–10% testosterone increase; more consistent over 6+ months than hexarelin
- Once-daily oral dosing
- Yes. No suppression of endogenous GH pulsatility
- Convenient oral option; modest testosterone effects but excellent safety profile
- GHRP-2
- Ghrelin receptor agonist. Moderate GH release, lower cortisol spike than hexarelin
- 6–9% testosterone increase in men with subclinical hypogonadism
- 2–3× weekly injection
- Yes
- Weaker testosterone effect than CJC-1295/ipamorelin; rarely used as monotherapy
- Thymalin
- Thymic peptide. Immune modulation, minimal direct hormonal effect
- No measurable testosterone increase in controlled trials
- Varies. Typically 5–10 day cycles
- N/A. Does not interact with HPG axis
- No evidence for testosterone support; marketed incorrectly in some protocols