Tesamorelin vs sermorelin: how the two GHRH analogues differ

Both peptides send the same message to the same receptor, so the useful comparison is not about mechanism. It is about the molecule, how long each lasts, what was tested, in whom, and what regulators decided. On evidence, tesamorelin is far ahead: it has large placebo-controlled trials and a current licence. Sermorelin has a real clinical history, but it was built in children with growth hormone (GH) deficiency and in small groups of older men, and no product is on the US market now.

Neither has been tested head to head against the other, so statements that one is “stronger” or “better” for a given goal are not supported by direct evidence. Full details of each are in our tesamorelin guide and sermorelin guide.

Natural GHRH is 44 amino acids long. Researchers found early on that the first 29 carry the hormone’s GH-releasing activity, and sermorelin is exactly that fragment, made synthetically with an amide at the end. A 1999 review described it as the shortest synthetic peptide with the full biological activity of GHRH ^[7].

Tesamorelin goes the other way. It keeps all 44 amino acids and adds a six-carbon hexenoyl chain to the tyrosine at position one; the US prescribing information gives its molecular weight as 5,135.9 Da for the free base ^[1]. The result is a molecule 15 amino acids longer than sermorelin, though both are small by protein standards.

The tesamorelin peptide sold for research is meant to be the same molecule as the licensed drug, but it is not the licensed product. Its identity and content depend on the supplier; our guide to what research peptides are explains the distinction.

Tesamorelin and sermorelin both bind the GHRH receptor on somatotroph cells in the anterior pituitary and trigger GH release, which raises IGF-1. The Egrifta label reports that tesamorelin binds and stimulates human GHRH receptors in vitro with similar potency to the body’s own hormone, and that no clinically significant changes in TSH, LH, ACTH or prolactin were seen in its trials ^[1]. The sermorelin review likewise described its effect as specific to GH release from the anterior pituitary ^[7].

Because both work through the pituitary, both depend on it. Neither can raise GH in someone whose pituitary cannot respond, and both remain subject to the body’s own brakes, somatostatin and IGF-1 feedback. The Egrifta label lists disruption of the hypothalamic-pituitary axis, for example after pituitary surgery or head irradiation, as a contraindication ^[1].

Tesamorelin’s stabilising cap is sometimes read as making it long-acting. It is not. The Egrifta WR label gives a mean elimination half-life of 11 minutes after a subcutaneous injection in healthy people, and an absolute bioavailability under 4% for subcutaneous injection of the older formulation ^[1]. The trials gave it once a day ^[2].

Sermorelin is shorter still. In ten healthy men given a constant intravenous infusion, GHRH(1-29), the sequence of sermorelin, disappeared with a half-time of about 4.3 minutes ^[10]. That short action helps explain a pattern in the adult studies: twice-daily injections raised IGF-1 in older men ^[8], while a single nightly injection raised night-time GH without moving IGF-1 ^[9].

The genuinely long-acting GHRH analogue is CJC-1295 with DAC, which binds albumin in the blood. It is a third molecule with its own, thinner evidence.

Tesamorelin’s licence rests on two multicentre phase 3 trials in people with HIV on antiretroviral therapy who had gained abdominal fat. In the first, 412 patients received 2 mg daily or placebo for 26 weeks; CT-measured visceral fat fell 15.2% with tesamorelin and rose 5.0% with placebo, with improvements in triglycerides and the cholesterol ratio and no significant difference in glucose measures ^[2]. Pooling both trials, 806 patients in all, gave a treatment effect of about -15% on visceral fat and no significant change in fat under the skin ^[3].

In the extension, the reduction held at about -18% over 52 weeks of continued treatment, and the fat came back when treatment stopped ^[4]. Outside HIV, a 20-week randomised trial in 152 adults aged 55 to 87 found a favourable effect of 1 mg nightly on a composite cognitive score, with a 117% rise in IGF-1 and a 7.4% fall in body fat; mild adverse events were reported by 68% on tesamorelin and 36% on placebo ^[5].

Sermorelin’s main trial was in children. The Geref International Study Group treated 110 previously untreated prepubertal children with GH deficiency with 30 µg/kg under the skin at bedtime for up to a year. Height velocity rose from 4.1 cm a year at baseline to 8.0 cm at six months and 7.2 cm at twelve, and 74% were judged good responders at six months ^[6]. The 1999 review added that sermorelin’s gains in height velocity were smaller than those with daily recombinant GH in the studies available, and that its effect on final adult height had not been established ^[7].

In adults the data are small. Ten healthy older men given 1 mg twice daily for 14 days reached 24-hour GH and IGF-1 levels no longer different from young men, without changes in glucose or blood pressure ^[8]. Eleven men aged 64 to 76 given 2 mg once nightly for six weeks had more night-time GH but no change in IGF-1, weight, body composition or lipids; two of six strength measures improved ^[9]. There are no large adult trials of sermorelin for body composition or ageing.

The Egrifta WR prescribing information lists an initial US approval of 2010 and an indication for reducing excess abdominal fat in HIV-infected adults with lipodystrophy. It also states that the drug is not indicated for weight loss, noting a weight-neutral effect, and that long-term cardiovascular safety has not been established ^[1].

Sermorelin acetate was approved in the US as Geref in two forms: a 0.05 mg ampoule approved on 28 December 1990 for testing the pituitary’s ability to secrete GH, and 0.5 mg and 1.0 mg vials approved on 26 September 1997 for idiopathic GH deficiency in children with growth failure. EMD Serono discontinued both in 2008 and the FDA withdrew the approvals with effect from 18 June 2009. In March 2013 the FDA published a determination that Geref was not withdrawn for reasons of safety or effectiveness, which allows generic applications if other requirements are met ^[11]. DailyMed, the US label database, lists no current sermorelin product ^[12].

So sermorelin was neither banned nor withdrawn as ineffective, but there is no sermorelin label to consult today, while tesamorelin has a current one.

Tesamorelin’s phase 3 trials used 2 mg injected under the skin once daily ^[2][3]. The current Egrifta WR label gives 1.28 mg once daily, injected into the abdomen, and states that Egrifta WR and the older Egrifta SV are not substitutable because their doses differ ^[1]. The cognition trial used 1 mg nightly ^[5].

Sermorelin was used as a single intravenous 1 µg/kg dose for diagnosis and as 30 µg/kg under the skin at bedtime for children ^[7][6]. The older-men studies used 0.5 mg or 1 mg twice daily ^[8] and 2 mg once nightly ^[9]. The two peptides were therefore studied on different scales, per kilogram in children and as fixed milligram doses in adults, which is one more reason their doses cannot be compared directly. These are figures reported in the cited sources, not recommendations; for laboratory unit conversions, see our peptide calculator.

Tesamorelin’s side effects are well documented because of its licence. The label lists joint pain, injection-site redness and itching, pain in the extremities, swelling of the lower legs and muscle pain as the reactions reported by more than 5% of patients. Injection-site reactions occurred in 25% on tesamorelin and 14% on placebo over the first 26 weeks, and 5% on tesamorelin against 1% on placebo developed an HbA1c of 6.5% or more ^[1]. The label also warns about fluid retention, raised IGF-1, hypersensitivity reactions and a possible effect on existing cancers, and contraindicates it in active malignancy and pregnancy ^[1].

Sermorelin’s reported side effects were mostly transient facial flushing and pain at the injection site ^[7]. Flushing is a known effect of GHRH itself: 16 of 18 men had one to three minutes of mild flushing after an intravenous dose of the full-length hormone ^[14]. Sermorelin has far less safety data overall, and the adult studies were too small to detect the fluid, glucose or IGF-1 effects that the tesamorelin trials found.

Neither safety profile transfers automatically to research-grade vials, whose purity and peptide content are unknown until independently tested. A 2026 review of GH-axis peptides noted this uncertainty around unregulated products ^[15].

If the question is visceral fat, the trial evidence belongs to tesamorelin, and specifically to people with HIV-associated fat gain; outside that group it has not been shown to help with weight. If the question is the diagnosis or treatment of GH deficiency in children, the historical evidence belongs to sermorelin, though that product is no longer made. For muscle growth, anti-ageing or athletic performance, neither has trial evidence in healthy adults, and both are banned in sport.

Online discussions often present sermorelin as a gentler or more natural option. The data do not measure gentleness. What they show is that sermorelin is shorter-acting and was less effective than daily GH in children ^[7], and that tesamorelin, at its licensed dose, produced measurable effects along with measurable side effects ^[1].

No study has given tesamorelin and sermorelin together, and there is no published data on the combination’s effects or safety. The research on combining GH secretagogues concerns a different pairing: a GHRH signal plus a ghrelin-receptor signal, which in healthy men released more GH than either alone ^[14]. Tesamorelin and sermorelin both deliver the GHRH signal through the same receptor, so that synergy finding does not apply to them.

The three-way search usually adds ipamorelin, which belongs to another class. Ipamorelin is a five-amino-acid ghrelin-receptor agonist that was never licensed, and its single efficacy trial came up negative. Our head-to-head pages cover those pairs: ipamorelin vs sermorelin and tesamorelin vs ipamorelin. The GHRH-plus-ghrelin-mimetic idea is covered on our page about CJC-1295 and ipamorelin.

WADA’s 2026 list names both in section S2 among the GHRH analogues, prohibited in and out of competition ^[13]. Medsafe classifies both as prescription medicines in New Zealand ^[16]. For what applies to buying research-grade material in each market, see our legal status overview and the US legal status page.

Prices for both vary widely between suppliers. Compare tesamorelin prices and sermorelin prices per milligram rather than per vial. Check that the mass on a certificate of analysis matches the molecule, since a 44-amino-acid peptide and a 29-amino-acid one are easy to tell apart by mass spectrometry; our guide on reading a COA shows where the mass appears, and third-party tested suppliers publish outside lab reports.