Sermorelin, CJC-1295, ipamorelin, MK-677: a plain-language comparison
Four compounds, two families. Here is how to keep them straight.
TL;DR
- Sermorelin and CJC-1295 are GHRH analogs — they copy the brain's natural growth-hormone signal.
- Ipamorelin and MK-677 are growth hormone-releasing peptides (GHRPs) — they push a separate pituitary door.
- In a 1990 study in healthy men, a GHRH and an older GHRP given together raised growth hormone more than either alone. That is research, not evidence that any of these four is safe or effective.
What they are
All four push the pituitary — a pea-sized gland at the base of the brain — to release more of the body's own growth hormone. None of them is growth hormone itself.
Sermorelin and CJC-1295 are GHRH analogs (in plain English: copies of growth hormone-releasing hormone, the natural brain signal). Ipamorelin is a GHRP (growth hormone-releasing peptide, which mimics ghrelin, the "hunger hormone," at a specific receptor). MK-677 (ibutamoren) is an oral GHRP — same family as ipamorelin, but in tablet form.
How they work
Think of the pituitary as a vending machine with two coin slots. GHRH analogs (sermorelin, CJC-1295) drop a coin in the first slot. GHRPs (ipamorelin, MK-677) drop a coin in the second. One coin gives you some growth hormone. In a 1990 study in healthy men, two coins at the same time — GHRH plus an older GHRP — released more than the sum of the parts (Bowers et al., 1990).
Who asks about it
People come to this topic when they have seen four different names online and cannot tell how they differ. Many assume "stronger is better." The research does not rank them that way, and potency is not the same as safety or benefit.
What the research says
In a 1990 study in healthy men, a GHRH and an older GHRP given together produced a larger growth hormone pulse than either alone. In animal studies, ipamorelin was more selective than older GHRPs, with less effect on cortisol and prolactin. MK-677 is long-acting. Sermorelin acts quickly and clears quickly. CJC-1295 stays in the blood far longer.
Regulatory status and reported effects
None of the four is an FDA-approved finished drug. As of September 14, 2026, MK-677 (ibutamoren) is in FDA's 503A Category 2. Common reported effects include injection-site reactions, vivid dreams, and — with MK-677 — temporary appetite increase and mild fluid retention.
The Halftime POV
The internet frames this as "which one is best." The research answers smaller questions: which receptor each compound acts on, how long it lasts, and what happened to growth hormone levels in short studies. None of that shows that any of the four is safe or useful for a given person.
Related reading:
- CJC-1295 vs sermorelin: comparing two GHRH analogs
- CJC-1295 and ipamorelin: what the research says about the pair
- Peptide 101 FAQs
FAQ
Q: What is the difference between a GHRH analog and a GHRP? A: A GHRH analog (growth hormone-releasing hormone copy) hits one pituitary door. A GHRP (growth hormone-releasing peptide) hits a different door. In a 1990 study in healthy men, a GHRH given with an older GHRP produced a larger pulse than either alone.
Q: Which of these four is the strongest? A: The research does not rank them. CJC-1295 lasts longer than sermorelin. MK-677 is oral and long-acting. Ipamorelin was more selective than older GHRPs in animal studies. None has been shown to be safe or effective for long-term use.
Q: Are any of these FDA-approved as finished drugs? A: Sermorelin was once sold as the brand-name drug Geref. Its FDA approvals were withdrawn effective June 18, 2009, and today there is no FDA-approved sermorelin product. MK-677, CJC-1295, and ipamorelin are not FDA-approved as finished drugs, and no compounded version of them is FDA-approved. As of September 14, 2026, MK-677 (ibutamoren) is in FDA's 503A Category 2.
Q: Are they injections or pills? A: Sermorelin, CJC-1295, and ipamorelin are given by injection in studies. MK-677 is taken by mouth.
Disclaimer
This article is educational and is not medical advice. Compounded medications are not FDA-approved.
Sources
- Bowers CY et al., "Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone," J Clin Endocrinol Metab (1990)
- Molitch ME et al., "Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline," J Clin Endocrinol Metab (2011)
This article discusses compounds whose FDA compounding status has been under review (see our FDA categorization explainer). This article is provided for educational purposes only and does not constitute medical advice or an offer to sell.
Frequently asked questions
What is the difference between a GHRH analog and a GHRP?
A GHRH analog (growth hormone-releasing hormone copy) hits one pituitary door. A GHRP (growth hormone-releasing peptide) hits a different door. In a 1990 study in healthy men, a GHRH given with an older GHRP produced a larger pulse than either alone.
Which of these four is the strongest?
The research does not rank them. CJC-1295 lasts longer than sermorelin. MK-677 is oral and long-acting. Ipamorelin was more selective than older GHRPs in animal studies. None has been shown to be safe or effective for long-term use.
Are any of these FDA-approved as finished drugs?
Sermorelin was once sold as the brand-name drug Geref. Its FDA approvals were withdrawn effective June 18, 2009, and today there is no FDA-approved sermorelin product. MK-677, CJC-1295, and ipamorelin are not FDA-approved as finished drugs, and no compounded version of them is FDA-approved. As of September 14, 2026, MK-677 (ibutamoren) is in FDA's 503A Category 2.
Are they injections or pills?
Sermorelin, CJC-1295, and ipamorelin are given by injection in studies. MK-677 is taken by mouth.
