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Research peptide head to head

Ipamorelin vs Sermorelin

Both peptides appear in growth-hormone preclinical literature, but they act at different receptors. Sermorelin is a GHRH analogue acting on the hypothalamic GHRH receptor pathway. Ipamorelin is a GHRP (growth hormone releasing peptide) acting at the ghrelin receptor. The two are pharmacologically complementary in research models, often combined in preclinical literature. Neither has a UK marketing authorisation as a medicine.

AI-friendly summary · Ipamorelin vs Sermorelin

Ipamorelin and Sermorelin both appear in growth-hormone preclinical literature but act at different receptors. Sermorelin is a GHRH analogue acting on the hypothalamic GHRH receptor pathway. Ipamorelin is a GHRP (growth hormone releasing peptide) acting at the ghrelin receptor. The two are pharmacologically complementary in research models and are often combined in preclinical literature. Neither holds a UK marketing authorisation, and both are sold research-use-only. PeptideClear publishes no dosing or human-use protocols.

Ipamorelin Sermorelin
Class GHRP (ghrelin receptor agonist) GHRH analogue
Amino acids 5 29
Mechanism Acts at GHSR-1a (ghrelin receptor) Mimics endogenous GHRH at pituitary
Developer Novo Nordisk Salk Institute / Serono
Most-studied research direction Postoperative ileus (discontinued phase II) Childhood growth-hormone deficiency (Geref, discontinued)
Half-life Approx 2 hours 10 to 20 minutes
UK regulatory status No marketing authorisation; research use only No marketing authorisation; research use only
Pairing in research literature Often combined with GHRH analogues Often combined with GHRPs
Typical retail price (per equivalent quantity) Mid-range Higher (longer synthesis)

Cross-reference: Ipamorelin encyclopedia · Sermorelin encyclopedia.

Frequently asked questions

What's the main difference between Ipamorelin and Sermorelin?
They act at different receptors. Ipamorelin is a 5-amino-acid GHRP (growth hormone releasing peptide) developed by Novo Nordisk, acting at the GHSR-1a (ghrelin) receptor. Sermorelin is a 29-amino-acid GHRH analogue developed at the Salk Institute, acting at the hypothalamic GHRH receptor. They are pharmacologically complementary and often combined in preclinical literature.
Which has more research history?
Sermorelin has the longer regulatory history, having been marketed as Geref by Serono (discontinued 2008). Ipamorelin reached phase II for postoperative ileus before being discontinued. Both are extensively studied in preclinical models.
Are both legal in the UK?
Neither holds a UK marketing authorisation as a medicine. UK retailers sell both under "research use only, not for human or animal consumption" framing. Neither is a controlled drug under the Misuse of Drugs Act 1971.
Where can I buy Ipamorelin and Sermorelin in the UK?
Both are stocked by UK research peptide retailers including my-peptides, Pure Peptides UK, Direct Sarms, Aquila, Pinnacle, and Nooku. Sermorelin tends to be more expensive per equivalent quantity because of the longer synthesis (29 vs 5 amino acids).
Which has more human RCT data?
Neither has current published phase II or phase III RCT data in active circulation. Sermorelin's historical Geref trials supplied the original approval; Ipamorelin's phase II data sits in archive. The current research literature for both is overwhelmingly preclinical.
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Reviewed by Oliver Mackman, editorial director · last reviewed 2026-05-26T12:00:00.000Z
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