Editorial note: this article summarises published research on tesamorelin and sermorelin. Baclabs does not sell tesamorelin, sermorelin or any peptide; we supply bacteriostatic water and reconstitution consumables. Nothing here is medical advice.
Tesamorelin vs sermorelin is a comparison between two analogues of the same hormone that ended up in very different places. Both are synthetic versions of growth hormone-releasing hormone (GHRH), both act on the GHRH receptor in the pituitary, and both raise growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Tesamorelin holds a current US licence, for a single narrow indication backed by two phase 3 trials. Sermorelin acetate was licensed for children in 1997, discontinued in 2008, and survives in the US as a compounded product marketed to adults for “anti-ageing”, a use it was never trialled for.
This article covers the structure of each, the evidence for tesamorelin in visceral fat, what the sermorelin trials measured, the licensed doses, and how the two are reconstituted. Context on the wider class is in the growth hormone secretagogues pillar.
Two GHRH analogues, two structures
Native human GHRH is 44 amino acids long, but the first 29 are enough for full receptor activity. Sermorelin is exactly that fragment, GHRH(1-29)-NH2, with a molar mass of about 3,358 g/mol [1]. Because it is otherwise unmodified, it is broken down by the same enzymes that clear native GHRH and its action is brief.
Tesamorelin keeps the full 44-amino-acid sequence and adds a trans-3-hexenoic acid group at the N-terminus. The modification slows enzymatic cleavage, but the compound is still short-lived: the label gives a mean elimination half-life of 26 minutes in healthy subjects and 38 minutes in HIV-infected patients after subcutaneous injection [2]. Both drugs therefore produce a GH pulse timed to each injection rather than a sustained elevation, in contrast to CJC-1295 with DAC, which is albumin-bound and acts for days.
Tesamorelin: the evidence for visceral fat
Tesamorelin was approved by the FDA in 2010 as Egrifta for “reduction of excess abdominal fat in HIV-infected patients with lipodystrophy” [2][3]. Lipodystrophy in this setting is a redistribution of fat, associated with older antiretroviral regimens, in which visceral adipose tissue (VAT) around the organs accumulates. The indication is that specific population, not abdominal fat in general.
The pivotal trial randomised 412 HIV patients with abdominal fat accumulation to 2 mg tesamorelin or placebo by daily subcutaneous injection for 26 weeks. VAT, measured by CT, fell 15.2 per cent on tesamorelin and rose 5.0 per cent on placebo. IGF-1 rose 81 per cent in the treatment group. Triglycerides fell by 50 mg/dL versus a 9 mg/dL rise on placebo. Adverse events did not differ significantly between groups overall, although more patients on tesamorelin withdrew because of one [4].
In the pooled analysis of both phase 3 trials, 806 patients were randomised 2:1 to tesamorelin 2 mg (n=543) or placebo (n=263). At 26 weeks VAT changed by −24 ± 41 cm² versus +2 ± 35 cm², a treatment effect of −15.4 per cent. Subcutaneous abdominal fat was not meaningfully different between groups. Patients who continued for 52 weeks reached −35 ± 50 cm² (−17.5 per cent) with a 3.4 cm reduction in waist circumference, and mean IGF-1 rose by 108 ng/mL against −7 ng/mL on placebo. No clinically meaningful differences in glucose parameters were seen at 26 or 52 weeks [5].
The 52-week extension study contains the finding that matters most for anyone considering tesamorelin for belly fat: patients re-randomised from tesamorelin to placebo at week 26 regained visceral fat. The authors state that “upon discontinuation of tesamorelin, VAT reaccumulated” and that the effects “do not last beyond the duration of treatment” [6]. Tesamorelin manages visceral adiposity while it is being taken; it does not reset it.
Licensed dose and label warnings
The original Egrifta label specifies 2 mg once daily by subcutaneous injection into the abdomen, supplied as 1 mg vials reconstituted with sterile water for injection to 1 mg/mL and injected immediately [2]. The later Egrifta SV formulation is a single 2 mg vial reconstituted with 0.5 mL of sterile water; the dose is 1.4 mg (0.35 mL) once daily [3]. Both labels state the reconstituted solution must not be refrigerated or frozen and must be used at once, which is why sterile water rather than a preserved diluent is specified.
Tesamorelin is contraindicated where the hypothalamic–pituitary axis is disrupted, in active malignancy, in pregnancy and in hypersensitivity. It requires IGF-1 monitoring, with discontinuation considered if IGF-1 stays persistently above 3 standard deviation scores, and glucose testing before and during treatment because new diabetes occurred in 5 per cent of treated patients versus 1 per cent on placebo. Common reactions are arthralgia, injection-site erythema and pruritus, extremity pain, peripheral oedema and myalgia [3]. About half of patients developed anti-tesamorelin antibodies by 26 weeks, without apparent loss of efficacy [2]. Tesamorelin has no UK marketing authorisation.
Sermorelin acetate: history, withdrawal and what the trials showed
Sermorelin was approved by the FDA in 1997 under the brand Geref, for treatment of children with GH deficiency or growth failure and as a diagnostic agent for assessing pituitary GH reserve [1]. The paediatric evidence is real. In the Geref International Study Group trial, 110 previously untreated prepubertal GH-deficient children received 30 mcg/kg once daily by subcutaneous injection for up to a year; mean height velocity rose from 4.1 ± 0.9 cm/year at baseline to 8.0 ± 1.5 cm/year at six months and 7.2 ± 1.3 cm/year at twelve months [7].
The manufacturer discontinued Geref in 2008 for commercial reasons. In March 2013 the FDA published a formal determination that the 0.5 mg and 1.0 mg vials and the 0.05 mg diagnostic ampoule “were not withdrawn from sale for reasons of safety or effectiveness” [8]. That finding is what allows US compounding pharmacies to continue preparing sermorelin, and it is why sermorelin acetate sits in Category 1 of the FDA’s 503B bulks list as a component of a previously approved drug [9], while the unlicensed GHRPs were pushed into Category 2 in 2023.
What sermorelin does not have is adult outcome data. The licensed indication was paediatric; no phase 3 trial has tested sermorelin for body composition, sleep, skin, cognition or longevity in adults. The “anti-ageing” positioning rests on the mechanism (raising endogenous GH and IGF-1), not on trials of sermorelin for those outcomes. It is reasonable to describe sermorelin as a well-characterised short-acting GHRH analogue with a paediatric safety record; it is not reasonable to describe it as proven for adult anti-ageing.
Tesamorelin vs sermorelin head-to-head
| Tesamorelin | Sermorelin acetate | |
|---|---|---|
| Structure | GHRH(1-44) with N-terminal trans-3-hexenoyl group | GHRH(1-29)-NH2 |
| Half-life | 26–38 min [2] | Short (minutes); not stated on label seen |
| Licensed indication | Excess abdominal fat in HIV lipodystrophy (US, 2010) [2][3] | Paediatric GHD and diagnostic (US, 1997; discontinued 2008) [1][8] |
| Licensed dose | 2 mg daily (Egrifta); 1.4 mg daily (Egrifta SV) [2][3] | 30 mcg/kg daily in the paediatric trials [7] |
| Key outcome data | VAT −15% at 26 wk, −17.5% at 52 wk; regained on stopping [4][5][6] | Height velocity 4.1 to 8.0 cm/yr in children [7] |
| Adult body-composition trials | Yes, in HIV patients | None |
| Diluent on label | Sterile water, single use, inject immediately [2][3] | Not applicable (discontinued); compounded products vary |
| UK status | No marketing authorisation | No marketing authorisation |
Reconstitution and diluent
Tesamorelin’s label answers the diluent question for that product: sterile water for injection, single use, discard anything left [2][3]. That is a single-dose product design, not a general rule for peptides. Compounded sermorelin and the research-grade GHRH analogues sold in 2 mg and 5 mg lyophilised vials are drawn from repeatedly over weeks, and a multi-dose vial needs a preserved diluent. Bacteriostatic water contains 0.9 per cent benzyl alcohol and supports multi-dose use for up to 28 days after first puncture; the reasoning is set out in bacteriostatic water vs sterile water and the storage limits in bacteriostatic water storage and shelf life.
The maths follows the standard formula: concentration = peptide mass ÷ diluent volume. A 2 mg vial with 1 mL gives 2 mg/mL = 2,000 mcg/mL, so each unit on a U-100 insulin syringe (0.01 mL) contains 20 mcg. A 5 mg vial with 2.5 mL gives the same 2,000 mcg/mL. Full tables and worked examples are in reconstituting GHRPs and GHRHs.
Multi-dose vials need a preserved diluent. Baclabs supplies UK-stocked bacteriostatic water in 30 mL vials; see the reconstitution guide for the maths.
Frequently asked questions
Does tesamorelin work for belly fat?
In HIV patients with lipodystrophy, 2 mg daily reduced visceral fat by about 15 per cent over 26 weeks and 17.5 per cent over 52, with little effect on subcutaneous fat [4][5]. The fat returned when treatment stopped [6]. There are no phase 3 trials in people without HIV, and the licence does not cover general abdominal fat.
What is the licensed tesamorelin dose?
The original Egrifta label is 2 mg subcutaneously once daily, given as two 1 mg vials reconstituted with sterile water [2]. Egrifta SV is 1.4 mg (0.35 mL of a 2 mg vial reconstituted with 0.5 mL sterile water) once daily [3]. Both are injected into the abdomen and used immediately after mixing.
Why was sermorelin (Geref) discontinued?
The manufacturer discontinued Geref in 2008 for commercial reasons. The FDA’s 2013 Federal Register determination states the products were not withdrawn for reasons of safety or effectiveness [8], which is the legal basis on which US compounding pharmacies still prepare sermorelin from bulk sermorelin acetate.
Is sermorelin proven for anti-ageing?
No. Sermorelin’s trial evidence is in GH-deficient children, where 30 mcg/kg daily roughly doubled height velocity [7]. No controlled trial has tested sermorelin for body composition, skin, sleep or longevity in adults. It raises GH and IGF-1 by a well-understood mechanism, but the adult anti-ageing claims are extrapolation.
Can tesamorelin or sermorelin be prescribed in the UK?
Neither has a UK marketing authorisation. A UK prescriber could in principle obtain either as an unlicensed import for a named patient under the Human Medicines Regulations 2012, taking personal responsibility for the decision. Products sold online as “research peptides” are not medicines and carry no assurance of identity or purity.
References
- Sermorelin. Wikipedia (citing FDA NDA records and Prakash & Goa 1999), accessed 2026
- EGRIFTA (tesamorelin for injection) prescribing information. US FDA, 2010
- EGRIFTA SV (tesamorelin for injection) prescribing information. US FDA, 2019
- Metabolic effects of a growth hormone-releasing factor in patients with HIV. Falutz et al., New England Journal of Medicine, 2007
- Effects of tesamorelin (TH9507) in HIV-infected patients with excess abdominal fat: a pooled analysis of two multicenter, double-blind placebo-controlled phase 3 trials with safety extension data. Falutz et al., Journal of Clinical Endocrinology & Metabolism, 2010
- Long-term safety and effects of tesamorelin, a growth hormone-releasing factor analogue, in HIV patients with abdominal fat accumulation. Falutz et al., AIDS, 2008
- Once daily subcutaneous growth hormone-releasing hormone therapy accelerates growth in growth hormone-deficient children during the first year of therapy. Geref International Study Group. Journal of Clinical Endocrinology & Metabolism, 1996
- Determination that GEREF (sermorelin acetate) injection was not withdrawn from sale for reasons of safety or effectiveness. US Federal Register, 2013
- Bulk drug substances nominated for use in compounding under section 503B. US FDA, updated March 2025
Disclaimer: This content is for educational purposes only and does not constitute medical advice. Bacteriostatic water is supplied for reconstitution of substances intended for research and for use as directed by a healthcare professional. Peptides and medicines discussed here may be unlicensed in the UK or prescription-only; consult a qualified clinician before using any medicine. Baclabs does not sell peptides.