Ipamorelin is a synthetic peptide that nudges the pituitary to release growth hormone. It was trialled by pharma for post-operative ileus, failed to win approval and was dropped. Today it is sold only as a research chemical and used off-label in wellness clinics — and it is banned at all times in tested sport by WADA.
Sermorelin is a synthetic copy of the first 29 [amino acids](/glossary "Amino acid: The building blocks of proteins. A peptide is a short chain of them linked together.") of natural GHRH — the hormone that tells the pituitary to release growth hormone. It was FDA-approved in 1990 as Geref for diagnosing and treating paediatric growth hormone deficiency, then discontinued from the US market in 2008 for commercial, not safety, reasons. No regulator currently licenses any sermorelin product. The molecule has come back as a heavily marketed compounded "anti-ageing" injectable from US wellness clinics — that is the form people are actually buying, and it has never been studied in healthy adults at that scale.
Both peptides share an evidence grade of C. The right choice depends less on the data and more on what you're trying to do — Ipamorelin for post-operative ileus (trialled), Sermorelin for paediatric growth hormone deficiency (treatment, historical).
The one indication ipamorelin reached human trials for. A randomised, placebo-controlled phase 2 study in bowel-resection patients (Beck et al. 2014) reported some signal on gastric motility but missed its primary endpoint. Development was halted.
Reliably raises GH in animals and healthy volunteers in short-duration studies. Whether sustained micro-pulses translate to meaningful long-term clinical outcomes in humans is not established.
FDA-approved in 1990 as Geref Diagnostic for the GHRH stimulation test in children with suspected growth hormone deficiency. Robust historical use; product no longer marketed.
FDA-approved as Geref for the treatment of children with idiopathic growth hormone deficiency. Documented growth response in trials; superseded by recombinant human GH (somatropin) on convenience and efficacy. Withdrawn from market 2008 for commercial reasons.
Small studies and review articles from the 2000s argued sermorelin could partially restore the diminished nocturnal GH pulse seen in older adults. Sample sizes are small, follow-up short, and no modern RCT has tested hard outcomes (body composition, function, cardiometabolic events) at scale.
In short-duration human trials ipamorelin was generally well tolerated, with the most common reports being injection-site reactions, mild headache and transient flushing. Longer-term safety in healthy adults using it for performance or anti-ageing reasons is unknown — there are no multi-month controlled trials in this population. Chronic stimulation of the GH/IGF-1 axis is the main theoretical concern: it could in principle worsen insulin resistance, drive water retention, accelerate diabetic retinopathy, or promote the growth of pre-existing tumours (IGF-1 is mitogenic). People with active cancer, a cancer history, diabetes, or who are pregnant or breastfeeding should not use it. Products sold as "ipamorelin" online are unregulated research chemicals — purity, sterility and dose-per-vial vary, and contamination is a real risk.
In the paediatric record, sermorelin was generally well tolerated. The commonest issues were local injection-site reactions (redness, swelling, pain), occasional flushing and headache, and rare cases of dysphagia or transient hyperactivity. Antibodies against sermorelin were detected in a minority of children on long-term therapy; clinical significance was unclear. Because sermorelin works through the body's own GH/IGF-1 axis, it shares the theoretical long-term concerns of any GH-raising therapy: potential effects on glucose tolerance, the theoretical concern that chronically elevated IGF-1 could accelerate growth of pre-existing cancers, and unknowns around long-term exposure in healthy adults who weren't the original target population. Pregnancy and breastfeeding: avoid. Compounded sermorelin from a 503A pharmacy is not FDA-reviewed for purity, potency or stability the way an approved drug is — and US compounding has had repeated quality incidents across drug categories. People with active malignancy, uncontrolled diabetes, severe respiratory or cardiac illness, or pituitary disease should not use it outside specialist care.
Both peptides share an evidence grade of C. The right choice depends less on the data and more on what you're trying to do — Ipamorelin for post-operative ileus (trialled), Sermorelin for paediatric growth hormone deficiency (treatment, historical).
Pepwyse comparison pages are generated from the same structured data behind each peptide profile. Want a different head-to-head? Use the compare picker or ask Ipamorelin directly via the Ask-Peppy button. Not medical advice — see how we grade evidence.