Ipamorelin vs sermorelin: two receptors, one hormone, and what the evidence can and cannot compare
A never-approved ghrelin mimetic against a once-approved GHRH analogue. Half-lives, histories, human evidence, and why no study has compared them.
At a glance
The short answer
Ipamorelin and sermorelin are both discussed for raising growth hormone, but they are different classes of drug acting on different receptors. Sermorelin is the first 29 amino acids of the body's own growth-hormone-releasing hormone, GHRH; it was approved in the United States in 1997 for children with growth hormone deficiency and withdrawn from the market in 2008 for commercial rather than safety reasons. Ipamorelin is a synthetic ghrelin-receptor agonist that was never approved.
No study has compared them head to head. Sermorelin's human record is larger and older; ipamorelin's is two trials. The two are often combined rather than chosen between, on the physiology that GHRH and ghrelin signals amplify each other.
Ipamorelin vs sermorelin in two minutes
Different receptors. Sermorelin is a GHRH analogue: it acts where the hypothalamus's own releasing hormone acts. Ipamorelin acts on the ghrelin receptor. Both end in the pituitary releasing growth hormone, which is why they are compared, and why they are also combined.
Different histories. Sermorelin (Geref) was an approved paediatric medicine from 1997 until its manufacturer withdrew it in 2008; it has since been widely available through US compounding pharmacies. Ipamorelin was developed by Novo Nordisk, failed a phase 2 trial for post-surgical gut recovery, and was never approved.
Evidence. Sermorelin has a real clinical record in children with growth hormone deficiency and diagnostic use in adults; its adult "anti-ageing" use has no trial support. Ipamorelin has a pharmacokinetic study and one failed trial. Neither has a trial for body composition, sleep or recovery in healthy adults.
Head to head. Nothing. No indexed study compares them.
Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.
Side by side, from each record
Each column states what that compound's own record says. Nothing is inferred across columns.
| Ipamorelin | Sermorelin | |
|---|---|---|
| Class | ghrelin mimetics | ghrh analogs |
| Target | ghrelin receptor (GHS-R1a) agonist | GHRH receptor agonist, GHRH(1-29) |
| Evidence tier | Human clinical trial | Approved label |
| Indexed publications | 63 | 579 |
| Randomized controlled trials | 2 | 39 |
| Human studies in ledger | 2 | 18 |
| Approval status | not approved · max phase 2 | approved (1990) |
What differs, point by point
| Ipamorelin | Sermorelin | |
|---|---|---|
| Class | Ghrelin mimetic (GHS-R1a agonist) | GHRH analogue (GHRH 1-29) |
| Origin | Synthetic pentapeptide, Novo Nordisk, 1990s | Fragment of the body's own GHRH; Serono, 1990s |
| Half-life | About 2 hours (human PK study) | About 10 to 20 minutes |
| Effect on cortisol and prolactin | Reported selective: little rise | Not applicable; GHRH does not act on those axes |
| Approval | Never approved | Approved US 1997 for paediatric GH deficiency; withdrawn 2008, commercial reasons |
| Human evidence | 2 trials: pharmacokinetics; failed ileus trial | Paediatric efficacy trials; adult diagnostic use; no adult wellness trials |
| Compounding in the US | Not permitted (interim 503A Category 2) | Has been available through compounding pharmacies |
| Sport status | WADA S2, prohibited at all times | WADA S2, prohibited at all times |
| Commonly reported use | 100 to 300 µg, 1 to 3 times daily | 200 to 500 µg nightly |
Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.
Studies that name both compounds
Indexed papers whose abstracts name both compounds, quoted. Read the design line on each card: naming both is not the same as comparing them.
How the two are discussed as choices
The community framing is that sermorelin is the "legal" or "prescribable" option because of its approval history and compounding availability, while ipamorelin is the "cleaner" option because of its reported selectivity for growth hormone over cortisol and prolactin. Both framings have something behind them and neither is an efficacy claim: sermorelin's approval was for children who lack the hormone, and ipamorelin's selectivity was shown in animals and healthy volunteers. Neither compound has been tested for the outcomes adults use them for. Because they act on different receptors, they are more often combined than chosen between, which is the same logic as the CJC-1295 and ipamorelin blend with a shorter-acting GHRH analogue. The tesamorelin and ipamorelin stack follows the same pattern with an approved GHRH analogue.
Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.
Open questions
- No study compares the two for any outcome.
- Sermorelin's adult wellness use has no trial support despite its paediatric approval history.
- Neither compound has been tested for body composition, sleep or recovery in healthy adults.
Questions people ask
Which is better, ipamorelin or sermorelin?
The evidence cannot say. They act on different receptors, neither has a trial for the uses adults pursue, and no study compares them.
Is sermorelin FDA approved?
It was, from 1997 for children with growth hormone deficiency, and was withdrawn in 2008 for commercial reasons. It is not currently an approved product, though it has been available through compounding.
Is ipamorelin FDA approved?
No. It failed a phase 2 trial and was never approved; it sits in Category 2 of the FDA's interim compounding list.
Can ipamorelin and sermorelin be taken together?
They are combined in communities on the reasoning that a GHRH signal and a ghrelin signal amplify each other. No trial has tested the pair.
Which has the longer half-life?
Ipamorelin, at about two hours in the human pharmacokinetic study, against roughly ten to twenty minutes for sermorelin.
Are they banned in sport?
Both, under WADA S2, at all times.
Reference card
- Comparison
- Ipamorelin vs Sermorelin
- Class
- ghrelin mimetics · ghrh analogs
- Target
- ghrelin receptor (GHS-R1a) agonist · GHRH receptor agonist, GHRH(1-29)
- Evidence tier
- Human clinical trial · Approved label
- Indexed publications
- 63 · 579
- Randomized controlled trials
- 2 · 39
- Human studies in ledger
- 2 · 18
- Approval status
- not approved · max phase 2 · approved (1990)
- Studies naming both
- 0 indexed papers
Each figure comes from that compound's own record. Print or save this card with its date.
Last reviewed and what changed
- · Reviewed by Adam Mirando, PharmD, on 2026-09-29.
- · Record created from measured demand (research/queue and the ipamorelin intent map); cross-class comparison written editorially; no head-to-head study exists and the page says so.