“Ipamorelin vs sermorelin” is one of the most common questions researchers ask about growth-hormone-axis peptides. This is the plain-English explanation; for the full attribute-by-attribute table, see our detailed ipamorelin vs sermorelin comparison. Everything here is for laboratory research use only.
The short answer
Ipamorelin and sermorelin act on different receptors and differ greatly in size. Sermorelin is a 29-amino-acid analogue of growth hormone-releasing hormone (GHRH 1-29) that targets the GHRH receptor. Ipamorelin is a much smaller five-amino-acid ligand of the ghrelin / growth-hormone-secretagogue (GHS) receptor. Same research area, two different receptor families.
Ipamorelin vs sermorelin at a glance
- Ipamorelin — 5 amino acids · ghrelin / GHS receptor · ~711.9 g/mol · CAS 170851-70-4
- Sermorelin — 29 amino acids · GHRH receptor · ~3358 g/mol · CAS 86168-78-7
Ipamorelin in brief
Ipamorelin is a synthetic pentapeptide studied as a selective ghrelin / GHS-receptor ligand. It is notable in the literature for a comparatively clean profile — activity on the growth-hormone axis with minimal reported effect on hormones such as ACTH and cortisol in preclinical models. For the full profile, see the ipamorelin research guide.
Sermorelin in brief
Sermorelin corresponds to the first 29 amino acids of GHRH — the N-terminal fragment recognised as the shortest sequence retaining full activity at the GHRH receptor. Because it is the “native fragment,” it often serves as a reference point against which modified GHRH analogues are compared. For the full profile, see the sermorelin research guide.
The key difference: two receptor families
The defining distinction is mechanism class. The GHRH receptor and the ghrelin / GHS receptor are two separate receptors that both feed into growth-hormone research. Sermorelin engages the first; ipamorelin engages the second. Because of this, the two are sometimes studied together precisely so a researcher can compare or combine the two pathways under controlled conditions. The choice between them is an experimental-design decision driven by which receptor is under investigation — it is not a ranking of potency for any applied or human purpose, and nothing here should be read as such.
Size and stability
The size gap is large: 5 residues versus 29, and roughly 712 versus 3,358 g/mol. Smaller and larger peptides behave differently in handling and in assays, which is another practical reason researchers distinguish them rather than treating them as interchangeable.
A note on CJC-1295
You will often see CJC-1295 (without DAC) mentioned in the same breath. Like sermorelin it is a GHRH (1-29)-based analogue, but with stabilising amino-acid substitutions. It therefore sits in the same receptor family as sermorelin, and contrasts with ipamorelin in the same way.
For the complete side-by-side table (class, length, molecular weight, receptor and CAS), see our ipamorelin vs sermorelin comparison page.
Frequently asked questions
No. They are chemically distinct peptides that act on different receptors: ipamorelin is a 5-amino-acid ghrelin / GHS-receptor ligand, while sermorelin is a 29-amino-acid GHRH-receptor analogue.
No. Ipamorelin acts on the ghrelin / GHS receptor; sermorelin acts on the GHRH receptor.
Sermorelin is much larger at 29 amino acids (~3358 g/mol); ipamorelin is a 5-amino-acid pentapeptide (~711.9 g/mol).
CJC-1295 (without DAC) is a GHRH (1-29)-based analogue like sermorelin, but with stabilising substitutions. It is in the GHRH-receptor family, contrasting with ipamorelin's GHS receptor.
See our dedicated comparison page, which sets out class, length, molecular weight, receptor target and CAS number side by side.
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