Tesamorelin vs Sermorelin: One Approved, One Discontinued

Tesamorelin and sermorelin are both synthetic analogs of growth-hormone-releasing hormone (GHRH), but their regulatory histories diverged: tesamorelin is FDA-approved today as Egrifta, for reducing excess abdominal fat in adults with HIV and lipodystrophy, while sermorelin was approved as Geref in 1990 and 1997 and discontinued by its maker in 2008. Each has a real human evidence base, in different populations, and we found no trial comparing the two directly.

Both act at the same pituitary receptor. What separates them is length, design and, above all, which trials were run.

At a glance

Two versions of the same hormone

GHRH is a hypothalamic hormone that signals the pituitary to release growth hormone. A 1999 review in BioDrugs (Prakash and Goa) describes sermorelin as a 29-amino-acid analog of human GHRH and the shortest synthetic fragment with the hormone's full biological activity.

Tesamorelin keeps the whole hormone. Its prescribing information describes it as the 44-amino-acid sequence of human growth-hormone-releasing factor with a hexenoyl group attached to the tyrosine at its start. That length has a regulatory consequence. Under a rule that took effect in March 2020, the FDA treats an amino acid chain longer than 40 residues as a protein regulated as a biological product, and Drugs@FDA now lists Egrifta's application as a biologics license, BLA 022505. Sermorelin, at 29 residues, sits below that line.

Neither is growth hormone. Both depend on a pituitary that can still respond. Our review of the growth-hormone axis explains why that distinction matters.

The evidence for tesamorelin

Tesamorelin was developed for one problem: fat that accumulates inside the abdomen in some people with HIV on antiretroviral therapy. Falutz and colleagues (New England Journal of Medicine, 2007) randomized 412 patients with HIV and excess abdominal fat to tesamorelin or placebo for 26 weeks. Visceral fat measured by CT fell 15.2% in the tesamorelin group and rose 5.0% on placebo. Triglycerides and the cholesterol ratio improved, IGF-1 rose 81%, and glucose measures did not differ significantly, though more tesamorelin patients withdrew because of adverse events.

A pooled analysis of the two phase 3 trials (Falutz and colleagues, Journal of Clinical Endocrinology and Metabolism, 2010) covered 806 patients. The treatment effect on visceral fat was a 15.4% reduction against placebo at 26 weeks, with no significant change in fat under the skin of the abdomen. Among patients who continued for another 26 weeks, the reduction was maintained to week 52.

Investigators have since studied it outside its label. In a randomized, double-blind trial of 61 people with HIV and fatty liver disease (Stanley and colleagues, Lancet HIV, 2019), liver fat fell by a relative 37% compared with placebo over 12 months. That is a research finding in one population, not an approved use.

The label is narrow and specific. It says Egrifta is not indicated for weight loss because its effect on weight is neutral, that long-term cardiovascular safety has not been established, and that treatment should be reconsidered in patients whose visceral fat does not fall. It is contraindicated in pregnancy, in active malignancy and in people with a disrupted hypothalamic-pituitary axis, and it carries warnings on elevated IGF-1, glucose intolerance and hypersensitivity reactions.

The evidence for sermorelin

Sermorelin's strongest data come from children who lacked growth hormone. In the Geref International Study Group trial (Thorner and colleagues, Journal of Clinical Endocrinology and Metabolism, 1996), 110 previously untreated children with growth hormone deficiency received it for up to a year in an open-label, multicenter study. Among the 86 eligible for the efficacy analysis, mean height velocity rose from 4.1 centimeters a year at baseline to 7.2 at twelve months. There was no placebo group.

In adults, the published work is small. Corpas and colleagues (Journal of Clinical Endocrinology and Metabolism, 1992) gave it to 10 healthy older men for two weeks and reported that growth hormone and IGF-1 rose toward levels seen in 9 young men. That is a hormone measurement over 14 days, not a health outcome.

What happened to Geref

According to a 2013 Federal Register notice, Geref was approved on December 28, 1990 as a test of the pituitary's ability to secrete growth hormone, and on September 26, 1997 for idiopathic growth hormone deficiency in children with growth failure. EMD Serono told the FDA in 2008 that it was discontinuing both products. In that notice, the FDA determined that Geref was not withdrawn from sale for reasons of safety or effectiveness. Drugs@FDA lists both Geref applications as discontinued and shows no other sermorelin product.

That determination is narrow. It means the discontinuation is not, on the FDA's finding, evidence against the drug. It does not mean any sermorelin product on the market today is Geref, or carries its approval. Sermorelin does not appear on the FDA's 503A category lists for nominated bulk substances, as updated May 14, 2026.

Regulatory status and sport

Tesamorelin is approved only as the Egrifta products, for one population. Material sold under the name outside a prescription is not Egrifta: in August 2026 the FDA cited a product sold online as "Tesamorelin" among the unapproved new drugs in a warning letter to an online peptide seller. Our coverage of those letters has the detail.

Both compounds are prohibited at all times under section S2 of the World Anti-Doping Agency's 2026 Prohibited List, which names sermorelin and tesamorelin as examples of GHRH analogs.

For sermorelin's comparison with the two other GHRH-axis peptides people most often ask about, see ipamorelin vs sermorelin vs CJC-1295.

Frequently asked questions

Is tesamorelin FDA-approved?

Yes, as Egrifta, approved in 2010 for reducing excess abdominal fat in adults with HIV and lipodystrophy. The label states it is not indicated for weight loss.

Is sermorelin FDA-approved?

It was. Geref was approved in 1990 and 1997 and discontinued in 2008. The FDA found that the discontinuation was not for safety or effectiveness reasons. No sermorelin product is approved today.

What is the difference between tesamorelin and sermorelin?

Sermorelin is the first 29 amino acids of GHRH. Tesamorelin is the full 44-amino-acid hormone with a chemical modification. Both act at the GHRH receptor, and they were studied in different populations.

Has tesamorelin been compared with sermorelin in a trial?

We found no published trial comparing them directly.

---

Sources:

• Prakash and Goa, BioDrugs, 1999 (review of sermorelin)
• Egrifta WR prescribing information, DailyMed, August 2026
• Drugs@FDA, Egrifta (tesamorelin), application 022505
• Theratechnologies, FDA approval of Egrifta WR, March 2025
• FDA, final rule: Definition of the Term "Biological Product," Federal Register, February 21, 2020
• Falutz et al., N Engl J Med, 2007 (412 patients with HIV)
• Falutz et al., J Clin Endocrinol Metab, 2010 (pooled phase 3, 806 patients)
• Stanley et al., Lancet HIV, 2019 (fatty liver disease in HIV, 61 patients)
• Thorner et al., J Clin Endocrinol Metab, 1996 (Geref International Study Group, 110 children)
• Corpas et al., J Clin Endocrinol Metab, 1992 (older and young men)
• FDA, determination that Geref was not withdrawn for reasons of safety or effectiveness, Federal Register, March 4, 2013
• Drugs@FDA, Geref (sermorelin acetate), NDA 020443
• FDA, Bulk drug substances nominated for use in compounding under section 503A (category lists, updated May 14, 2026)
• FDA warning letter to TXP Innovations LLC (Tex Peptides), August 24, 2026
• WADA 2026 Prohibited List, as published in the Dutch treaty series (S2.2.4)

Apart from the approved Egrifta products and the discontinued Geref products, no compound discussed here is FDA-approved. Nothing above is dosing guidance or a treatment claim. Research use only.