Ipamorelin vs Sermorelin: Approval History, Evidence and Lab Results

The biggest difference is regulatory history. Sermorelin is a fragment of the body's own growth-hormone-releasing hormone (GHRH) and was FDA-approved for two narrow uses as Geref. Its manufacturer notified FDA in 2008 that it was discontinuing the product, FDA withdrew the approvals effective June 18, 2009, and FDA determined in 2013 that the product was not withdrawn for reasons of safety or effectiveness. Ipamorelin is a synthetic ghrelin-receptor peptide that has never been approved by any regulator. No approved sermorelin product is on the US market today, so what buyers get is either compounded or grey-market material, not Geref.

At a glance

How they work differently

Your pituitary has two separate switches for releasing growth hormone. Sermorelin uses the one the brain normally uses, the GHRH receptor. Ipamorelin uses the ghrelin receptor, the one the stomach hormone ghrelin uses.

Sermorelin is the first 29 amino acids of human GHRH, the shortest piece that keeps the full activity of the natural hormone (Prakash and Goa 1999, BioDrugs). A 2006 commentary argues that because it works through the body's own release system, its effects remain under negative feedback from somatostatin, the hormone that reins in growth hormone release. The author contrasts that with injected growth hormone, which bypasses that control (Walker 2006, Clin Interv Aging). Note that the commentary is an argument for the mechanism, not a trial.

Ipamorelin was described in 1998 as the first "selective" growth hormone secretagogue. It acts through a receptor of the growth-hormone-releasing-peptide type and, in swine, did not raise ACTH or cortisol the way two related compounds did (Raun et al. 1998, Eur J Endocrinol). In healthy men it produced one short burst of growth hormone, with a blood half-life of about two hours (Gobburu et al. 1999, Pharm Res).

Both act on the pituitary, so both depend on it still being able to respond. FDA's ipamorelin review says ipamorelin would not be expected to raise growth hormone in people with absent pituitaries or severely damaged growth-hormone-producing cells (FDA briefing document on ipamorelin, October 2024); the same logic applies to sermorelin, which works on the same cells through the GHRH receptor (our inference, not an FDA statement).

What the evidence shows

No head-to-head trial exists. A PubMed search on September 30, 2026 for studies mentioning both ipamorelin and sermorelin returned only narrative reviews. Comparing numbers across separate studies is unreliable, because they enrolled different people, used different outcomes and were run decades apart. Here is each compound's best evidence. The longer versions are in our ipamorelin guide and sermorelin guide.

Sermorelin. FDA approved Geref twice. One product, approved December 28, 1990, was indicated for evaluating whether the pituitary could secrete growth hormone. The other, approved September 26, 1997, was indicated for children with idiopathic growth hormone deficiency and growth failure (Federal Register, March 4, 2013). Behind the pediatric use is an open-label multicenter study of 110 previously untreated children, 86 of whom were analyzed. Mean height velocity rose from about 4 cm a year at baseline to about 8 at six months and about 7 at twelve months, and the authors called it well tolerated (Thorner et al. 1996, J Clin Endocrinol Metab). A review of the evidence noted the data were limited and that sermorelin's growth effect had not been directly compared with somatropin, although increases in height velocity were smaller than those reported in children given somatropin (Prakash and Goa 1999).

For adults, the evidence is thin. The best-known human study, in 11 healthy older men, was uncontrolled: growth hormone release increased, IGF-1 did not, two of six strength measures and one endurance test improved, and body composition did not change (Vittone et al. 1997, Metabolism). We found no randomized, placebo-controlled trial of sermorelin for anti-aging, muscle or fat loss. The 2006 commentary is an argument for the approach, not a trial.

Ipamorelin. Beyond the pharmacology study, the only controlled trial tested it for return of bowel function after abdominal surgery. In 114 analyzed patients, the median time to a tolerated solid meal was about 25 hours with ipamorelin and about 33 hours with placebo, which was not statistically significant, and no secondary measure differed significantly (Beck et al. 2014, Int J Colorectal Dis). FDA's review says development for that use was reportedly discontinued because of the results, and that it found no data supporting ipamorelin for growth hormone deficiency (FDA briefing document, October 2024).

Put plainly, sermorelin has a genuine approval history and open-label pediatric data behind it, though for uses that differ from what most grey-market buyers want. Ipamorelin has a tested mechanism and one negative trial. For the adult claims that dominate the market, such as muscle, fat loss and anti-aging, the evidence for both is anecdotal. A June 2026 narrative review placed both in the growth-hormone-axis group of unapproved "research compound" peptides and stressed the uncertainty about product composition (Dominikowski et al. 2026, Front Endocrinol).

Side effects and risks compared

Sermorelin. In the pediatric literature, the most commonly reported adverse events were transient facial flushing and pain at the injection site (Prakash and Goa 1999). In the 110-child study, no adverse changes in general biochemistry or hormones were noted, and no change in fasting glucose (Thorner et al. 1996). The 11-man study reported no significant adverse effects (Vittone et al. 1997). All of those studies are decades old and small, and none reflects compounded or grey-market product. FDA's 2013 notice determined that Geref was not withdrawn for reasons of safety or effectiveness, which is a statement about why it stopped being sold, not a modern safety profile.

Ipamorelin. In the surgical trial, adverse events were reported by 87.5% of the ipamorelin group and 94.8% of the placebo group, and the authors called it well tolerated (Beck et al. 2014). That was a short hospital course in surgical patients. FDA's review of the same trial notes serious adverse events in 17.9% of ipamorelin patients and 15.5% of placebo patients, including two deaths in the ipamorelin group after bowel-resection complications (whether the drug played a role is unclear), and more hypokalemia (12.5% versus 3.4%) and hyperglycemia at discharge (14.3% versus 8.6%) on ipamorelin. Beyond that, FDA raises theoretical concerns. Ghrelin receptors are found in brain reward regions, and the ghrelin class could in principle affect reward processing. A mouse study of ghrelin found effects on fertilization and early embryo development, and FDA says whether ipamorelin does the same remains to be determined. FDA also found the nonclinical toxicity studies "too limited in scope and duration," and turned up two non-serious adverse-event reports tied to compounded products (FDA briefing document, October 2024). FDA's advisory committee voted 0 in favor, 12 against, 1 abstaining on listing either form of ipamorelin for compounding on October 29, 2024 (summary minutes). FDA's bulk substances page, current as of April 22, 2026, still lists ipamorelin acetate in Category 2 for 503B outsourcing facilities (added September 29, 2023).

What the lab tests show

These figures come from independent lab reports, mostly commissioned by buyers, counting only identified vendors. Our failure definition is an empty vial, purity under 95%, more than 20% under label, or more than 50% over.

Ipamorelin: 20 vials from 12 vendors, 18 reports, January 2025 to August 2026. Median purity was 99.77%. As of September 30, 2026, median dose came in 1.6% under label, which is unusual in our data, where most compounds run over. 6 vials were within 5% of label (ten were within 10% as of September 30, 2026); 2 were more than 20% under and 1 more than 20% over. 2 of 20 vials (10%) failed.

Sermorelin: 11 vials from 5 vendors, 9 reports. Median purity was 99.31%. Median dose was 1.2% over label, with 9 vials within 5% of label (all 11 were within 10% as of September 30, 2026). 0 of 11 vials failed.

The samples differ in size, 20 vials against 11, and each is spread across few vendors, so one vendor's batch can move any figure. That means the numbers cannot rank one compound against the other. What they showed as of September 30, 2026, is that sermorelin's dose accuracy has been consistently close to label so far, while ipamorelin's has been more spread out and skewed slightly under.

Here is who has the strongest independent lab record for ipamorelin right now. The table flags vendors with more than 5% failed vials, and a ranked vendor is not automatically a good one:

And here is how the ranked vendors for sermorelin look right now. With so few sermorelin vials in the database, this table may be short:

Buying smarter

Check each vendor's record for the specific compound: our ipamorelin results page and sermorelin results page show every report behind the scores, and a vendor needs five or more lab reports before we rank them. A perfect record built on one or two reports tells you little.

Because the sermorelin sold today is not Geref, the old approval does not vouch for any vial you can buy now. How to get a peptide tested covers ordering identity, purity and quantity testing on your own vial. Treat a vendor's posted COA as a starting point, and cross-check it with how to read a peptide COA and fake peptide COAs. If a report comes back failed, stop using that batch, tell anyone who bought from the same run, bring the report to the vendor, and submit it to VendorVerify.

Database figures without a date update automatically from VendorVerify's lab results; dated figures are snapshots. This isn't medical advice; ipamorelin is sold for research use only, and sermorelin is not currently available as an FDA-approved product in the United States.