CJC-1295, ipamorelin, sermorelin and tesamorelin are often grouped together as growth hormone peptides, which makes them sound like four versions of the same thing. They are not. Three mimic growth hormone releasing hormone and one works through a different receptor. One is an approved medicine for a very specific condition, one was approved decades ago and is no longer made, and two were never approved. The comparison is much easier once you stop treating them as interchangeable.
| Compound | Main pathway | Clinical position |
|---|---|---|
| CJC-1295 | Long acting GHRH analogue | Investigational; never approved |
| Ipamorelin | Ghrelin receptor (growth hormone secretagogue) | Investigational; never approved |
| Sermorelin | Short GHRH analogue | Formerly FDA approved; withdrawn in 2009 |
| Tesamorelin | GHRH analogue | FDA approved for excess abdominal fat in adults with HIV associated lipodystrophy |
None of the four has a UK marketing authorisation.
How is growth hormone normally controlled?
Growth hormone comes from the pituitary gland, and it is released in pulses rather than a steady stream. One signal that prompts release is growth hormone releasing hormone, GHRH, from the brain. Another route runs through the ghrelin receptor. That gives drug developers two basic options: imitate GHRH, or activate the ghrelin receptor with a growth hormone secretagogue. That is the main line dividing these four compounds.
Sermorelin
Sermorelin is the first 29 amino acids of natural GHRH, the part of the hormone that carries its activity. It has a genuine pharmaceutical history. In the US, as Geref, it was approved in 1990 as a diagnostic test of the pituitary's ability to release growth hormone and in 1997 for treating growth hormone deficiency in children with growth failure. In an open label study of 110 previously untreated children, average growth rate roughly doubled over the first six months, from 4.1 to 8.0 cm a year Human 1. The manufacturer discontinued both products in 2008, approval was withdrawn in 2009, and in 2013 the FDA determined that they had not been withdrawn for reasons of safety or effectiveness 2.
So sermorelin is not an internet research peptide invented by clinics. But its evidence is in children with a diagnosed deficiency. In a small uncontrolled study of eleven healthy men aged 64 to 76, six weeks of nightly injections raised night time growth hormone release and improved two of six strength measures, but did not change IGF-1, weight or body composition Human 3. And no approved sermorelin product exists today: what is sold now comes from compounding pharmacies or unregulated suppliers, and compounded products are not approved medicines.
CJC-1295
CJC-1295 is another GHRH analogue, engineered to last far longer. The best known form carries a drug affinity complex, DAC, which lets it bind albumin in the blood and gives it a half life of about a week. Two randomised, placebo controlled studies in healthy adults aged 21 to 61, published together in 2006, found that a single injection raised growth hormone for six days or more and IGF-1 for up to about eleven days, with an estimated half life of 5.8 to 8.1 days Human 4. They lasted 28 and 49 days and measured hormones, not muscle, fat, ageing or recovery, and CJC-1295 never went on to approval.
Is CJC-1295 just long acting sermorelin? It is a useful shortcut, since both act through GHRH signalling, but they are different molecules. Sermorelin mirrors the natural hormone; CJC-1295 was chemically engineered to act for days. Because natural growth hormone release comes in pulses, turning a short signal into a long one can change how the body responds. Same pathway does not mean same drug. And the version sold as CJC-1295 without DAC is different again: those 2006 trials used the DAC form, so their results do not describe it.
Ipamorelin
Ipamorelin takes the other route. It is a growth hormone secretagogue that works through the ghrelin receptor, not the GHRH receptor. In healthy men it produces a burst of growth hormone release, with a short half life of about two hours Human 5. That difference in route is why CJC-1295 and ipamorelin are often paired: two pathways into the same hormone system. It is a reasonable idea, but, as CJC-1295 + Ipamorelin explains, there is a large gap between that rationale and a proven combination.
Ipamorelin did reach human development, but not for bodybuilding or recovery. Its clinical programme tested it for postoperative ileus, the slow return of bowel function after surgery. In a randomised, placebo controlled phase 2 trial of 117 patients having bowel resection, ipamorelin was well tolerated, but patients did not tolerate a solid meal significantly sooner than on placebo, a median of 25.3 against 32.6 hours Human 6. That shows ipamorelin is a genuinely active molecule; it does not support the benefits clinics market it for.
Tesamorelin
Tesamorelin is the most clinically established of the four. It is a stabilised version of the full 44 amino acid GHRH, approved by the US FDA since 2010 to reduce excess abdominal fat in adults with HIV and lipodystrophy, a condition in which fat is lost from some areas of the body and can build up around the abdominal organs Regulator approved indication. It is sold in the US as Egrifta SV and, since the FDA approved a newer formulation in March 2025, as Egrifta WR; the two are not interchangeable. The label is specific: Egrifta WR "is not indicated for weight loss management as it has a weight neutral effect" 7.
The evidence behind it is of a different kind from the others. The first phase 3 trial, published in 2007, randomised 412 people with HIV and excess abdominal fat to daily tesamorelin or placebo for 26 weeks. Visceral fat, the deep abdominal fat measured by CT scan, fell by 15.2% on tesamorelin and rose by 5.0% on placebo; triglycerides and the cholesterol ratio improved, and glucose measures did not change significantly Human 8. A second phase 3 trial repeated the design, and a pooled analysis of 806 randomised patients found the reduction held to 52 weeks in those who stayed on treatment, again without clinically meaningful changes in glucose 9. Researchers measured the outcome the medicine was meant to change, which is much stronger evidence than a rise in a hormone level.
Tesamorelin has no UK or EU licence. Its European application was withdrawn in June 2012, when the European Medicines Agency's committee was of the provisional opinion that it could not be approved: the committee doubted the fat reduction had been shown to bring real health benefits, and considered the rise in IGF-1 a major safety concern with no long term safety data 10.
Does tesamorelin show that growth hormone peptides burn fat?
No. It shows that tesamorelin reduces visceral fat in the specific population it is approved for. It does not show that CJC-1295, sermorelin or ipamorelin will do the same, or that tesamorelin will do it in otherwise healthy people. That is evidence borrowing: the pathway sounds similar, so people assume the result transfers. It does not, automatically.
| Compound | Mechanism | Half life | UK status | Evidence |
|---|---|---|---|---|
| CJC-1295 with DAC | CJC-1295 is a modified version of GRF(1-29), the shortest fragment of human growth hormone releasing hormone that retains full biological activity. | Estimated terminal half life of 5.8-8.1 days in healthy adults after single subcutaneous or intravenous doses (Teichman 2006). | No UK marketing authorisation. | Limited evidence |
| Ipamorelin | Ipamorelin is an agonist at the growth hormone secretagogue receptor 1a, the receptor cloned by Howard and colleagues in 1996 and later identified as the target of the endogenous hormone ghrelin. | A short terminal half life of approximately 2 hours in healthy male volunteers after intravenous infusion, with dose proportional pharmacokinetics (Gobburu 1999). | No UK marketing authorisation. | Limited evidence |
| Sermorelin | Sermorelin is the identical N-terminal 29-residue sequence of endogenous human GHRH, amidated at the C-terminus. | Approximately 11 to 12 minutes after intravenous administration, as reported in the historical US prescribing information for the withdrawn product. | No current UK marketing authorisation. | Limited evidence |
| Tesamorelin | Tesamorelin is full length human GRF(1-44) carrying a trans-3-hexenoyl group on the N-terminal tyrosine. | Very short. | No UK or EU marketing authorisation. | High-quality evidence |
Which lasts longest?
CJC-1295 with DAC was designed to act for about a week. Sermorelin is short acting, ipamorelin produces a brief burst lasting hours, and tesamorelin is given daily. Duration is not a ranking, though. A longer hormonal signal may have different effects and different risks. How a drug behaves in the body tells you nothing about whether it produces the outcome you want.
Which is best for muscle?
There is no clinical basis for ranking these four as muscle building drugs in healthy people. CJC-1295 and ipamorelin change growth hormone signalling; sermorelin has a medical history in children's growth; tesamorelin changes visceral fat in HIV associated lipodystrophy. None of that amounts to a proven muscle building treatment for healthy adults, which would need trials measuring muscle mass, strength, function and safety in that population.
Which is safest?
The question cannot be answered with one name, because the evidence bases are not comparable. Tesamorelin has the most developed safety information: its two phase 3 trials enrolled 816 people, and 740 people with HIV received it in clinical trials, some for up to a year. Its label carries real warnings, including an increased risk of neoplasms (tumours), raised IGF-1, fluid retention, glucose intolerance or diabetes, and hypersensitivity reactions 7. Sermorelin's safety experience comes from children with a diagnosed deficiency treated under medical supervision, which says little about adults using compounded products today. For CJC-1295, the FDA has said it identified serious adverse events, including increased heart rate and a whole body vasodilatory reaction, and that clinical data are limited; for ipamorelin, it has raised concerns about impurities and immune reactions in compounded preparations, and notes serious adverse events, including death, reported in a published study in which it was given intravenously for gut motility 11.
All four are banned at all times in sport under the WADA Prohibited List, which covers growth hormone releasing hormone analogues and growth hormone secretagogues 12.
CJC-1295 with DAC
Limited evidenceGH secretagogues · 3 cited studies
Human data consist of two small, short, sponsor run pharmacodynamic studies in healthy volunteers measuring only growth hormone and IGF-1; the only other citation is a mouse study, no efficacy trial has ever been completed or published, and the single phase 2 trial was halted and never reported.
UK status. No UK marketing authorisation.
Ipamorelin
Limited evidenceGH secretagogues · 4 cited studies
Human data comprise a single phase 1 pharmacokinetic study and one well conducted phase 2 randomised trial in postoperative ileus that missed its primary endpoint (P=0.15) and all secondary endpoints; the remaining citations are preclinical, and there is no controlled human data of any kind for body composition, recovery or the other uses for which it is marketed.
UK status. No UK marketing authorisation.
Sermorelin
Limited evidenceGH secretagogues · 4 cited studies
Downgraded from 'mixed' on audit: the pivotal paediatric treatment study was open label and uncontrolled, the only cited adult study was open label in eleven men and found no change in IGF-1 or body composition, and no placebo controlled trial of sermorelin as treatment appears in the citation set at all. The former FDA approval, though genuine, is not itself controlled evidence.
UK status. No current UK marketing authorisation.
Tesamorelin
High-quality evidenceGH secretagogues · 4 cited studies
Two replicated multicentre phase 3 randomised placebo controlled trials pooling 816 participants, current FDA-approved labelling, and independent randomised placebo controlled trials in liver fat and cognition; all five citations verified against PubMed and ClinicalTrials.gov.
UK status. No UK or EU marketing authorisation.
The BioRx conclusion
All four influence the growth hormone axis, and that is largely where the similarity ends. Sermorelin is a short GHRH analogue with a past approval in children. CJC-1295 is a long acting experimental GHRH analogue. Ipamorelin works through the ghrelin receptor. Tesamorelin is an approved GHRH analogue with substantial evidence for one specific HIV related condition. The mistake is assuming that because all four can raise growth hormone, they deliver the same results. They do not share the same evidence, and in peptide science that matters more than the mechanism.
Frequently asked questions
What is the difference between CJC-1295 and ipamorelin?
CJC-1295 mimics growth hormone releasing hormone and, in its DAC form, lasts about a week. Ipamorelin acts through the ghrelin receptor and lasts a couple of hours. Neither is an approved medicine.
Is sermorelin better than ipamorelin?
They work differently and neither has been shown to be better for any adult use. Sermorelin was once approved for children with growth hormone deficiency; ipamorelin's published randomised trial, in bowel surgery, found no significant benefit over placebo.
Is tesamorelin approved?
In the US, yes, for reducing excess abdominal fat in adults with HIV associated lipodystrophy. Its label says it is not indicated for weight loss management, and it has no UK or EU licence.
Are growth hormone peptides legal in the UK?
None of these four has a UK marketing authorisation. Supplying them as medicines for human use without authorisation is unlawful under the Human Medicines Regulations 2012, and all four are banned in sport.
References
Studies marked "View study in BioRx" sit in the clinical studies index with their design and evidence grade.
- Thorner M, Rochiccioli P, Colle M, et al. (Geref International Study Group) (1996). Once daily subcutaneous growth hormone-releasing hormone therapy accelerates growth in growth hormone-deficient children during the first year of therapy. Journal of Clinical Endocrinology and Metabolism.PubMed · DOI · View study in BioRx
- FDA, Determination that GEREF (sermorelin acetate) was not withdrawn from sale for reasons of safety or effectiveness, Federal Register 2013
- Vittone J, Blackman MR, Busby-Whitehead J, et al. (1997). Effects of single nightly injections of growth hormone-releasing hormone (GHRH 1-29) in healthy elderly men. Metabolism.PubMed · DOI · View study in BioRx
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. Journal of Clinical Endocrinology and Metabolism.PubMed · DOI · View study in BioRx
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research.PubMed · DOI · View study in BioRx
- Beck DE, Sweeney WB, McCarter MD (Ipamorelin 201 Study Group) (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International Journal of Colorectal Disease.PubMed · DOI · ClinicalTrials.gov · View study in BioRx
- Egrifta WR (tesamorelin) prescribing information, DailyMed
- Falutz J, Allas S, Blot K, et al. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine.PubMed · DOI · View study in BioRx
- Falutz J, Mamputu JC, Potvin D, et al. (2010). Effects of tesamorelin (TH9507), a growth hormone-releasing factor analog, in human immunodeficiency virus-infected patients with excess abdominal fat: a pooled analysis of two multicenter, double-blind placebo-controlled phase 3 trials with safety extension data. Journal of Clinical Endocrinology and Metabolism.PubMed · DOI · View study in BioRx
- EMA, Withdrawal of the marketing authorisation application for Egrifta (tesamorelin), 2012
- FDA, Certain bulk drug substances for use in compounding that may present significant safety risks
- WADA, The Prohibited List
