Tesamorelin: Approved for One Indication, Studied for More

The short version

Tesamorelin (also called TH9507) is a 44-amino-acid synthetic analogue of human growth hormone-releasing hormone (GHRH). Its defining modification is a trans-3-hexenoic acid group on the N-terminus, which blocks cleavage by dipeptidyl peptidase-IV (DPP-IV), extending its stability relative to native GHRH.

Tesamorelin is the only FDA-approved compound on this desk. Its approved indication — established by NDA 022505 in November 2010 — is reducing excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy. Outside that specific population, all uses are off-label and investigational. A 2026 meta-analysis pooling five RCTs confirmed a mean visceral adipose tissue (VAT) reduction of 27.71 cm² and an increase in lean body mass of 1.42 kg across those trials ^[13].

Tesamorelin amplifies the body's own pulsatile growth hormone rhythm; it does not supply exogenous GH. Because approval is limited, and visceral fat reaccumulates upon discontinuation, the clinical picture is more constrained than some off-label discussions imply. This page summarizes the evidence and regulatory status; it is not medical advice.

What it is

Tesamorelin acetate is a synthetic 44-amino-acid peptide corresponding to GHRH(1-44)-NH2 — the full-length human growth hormone-releasing hormone sequence — with a trans-3-hexenoic acid group conjugated to its N-terminus. The empirical formula of the free base is C221H366N72O67S. It is supplied clinically as the acetate salt for injection.

The N-terminal modification is the pharmacological key: native GHRH is rapidly cleaved by DPP-IV at the His²-Ala³ bond, giving it a very short plasma half-life. The hexenoyl group sterically blocks that cleavage site, extending plasma stability and enabling a once-daily injection regimen. Tesamorelin acts on the GHRH receptor (GHRH-R) on anterior-pituitary somatotroph cells.

How it works

Tesamorelin binds the GHRH-R on pituitary somatotroph cells, activating the Gs/adenylyl-cyclase/cAMP/PKA signaling cascade. This stimulates synthesis and pulsatile secretion of the cell's own endogenous growth hormone (GH). The resulting GH then drives hepatic production of insulin-like growth factor-1 (IGF-1).

The GH/IGF-1 combination promotes preferential lipolysis — fat breakdown — in visceral adipose tissue, which is why the primary clinical endpoint in tesamorelin trials is visceral fat area by CT or MRI rather than total body weight. Because tesamorelin amplifies the body's own pulsatile GH rhythm rather than supplying a continuous exogenous GH bolus, its metabolic profile differs from recombinant growth hormone therapy — pulsatility is associated with better metabolic tolerability and preserved insulin sensitivity ^[16].

What the research shows

2026 meta-analysis (five RCTs, HIV lipodystrophy). Pooling five randomized controlled trials in HIV-associated lipodystrophy, tesamorelin reduced visceral adipose tissue by a mean of 27.71 cm² (95% CI -38.37 to -17.06; P<0.001), reduced trunk fat by 1.18 kg, reduced hepatic fat fraction by 4.28%, and increased lean body mass by 1.42 kg — all P<0.001, without serious adverse events ^[13].

Visceral fat and liver fat (JAMA RCT, 2014, n=50, HIV). In a 6-month randomized trial of 50 antiretroviral-treated HIV adults, tesamorelin 2 mg/day produced a treatment effect of -42 cm² in visceral fat (P=0.005) and reduced hepatic lipid-to-water ratio by a net 2.9% (P=0.003) ^[15].

GH pulsatility and insulin sensitivity (healthy men, n=13, 2011). Two weeks of tesamorelin 2 mg/day increased mean overnight GH by 0.5 µg/L (P=0.004) and raised IGF-1 by 181 µg/L (P<0.0001) without significantly affecting fasting glucose (P=0.93) or insulin-stimulated glucose uptake (P=0.61) ^[16].

52-week extension (HIV). In the 52-week program (n=273 tesamorelin, n=137 placebo), visceral fat reduction was sustained at -18% through 52 weeks (P<0.001 vs baseline). Upon discontinuation, visceral fat reaccumulated. Changes in glucose parameters over 52 weeks were not clinically significant ^[17].

FDA approval and hepatic safety. Tesamorelin received FDA approval (NDA 022505) in 2010 for HIV-associated lipodystrophy. The NIH LiverTox monograph assigns it a likelihood score of E (unlikely cause of clinically apparent liver injury), with no reported attributable liver-injury cases and no de novo serum-enzyme elevations in trials ^[14].

Reported effects, cautions & safety

No community-anecdote reports are compiled in this desk's source material for tesamorelin, and none are presented here. The following cautions are drawn directly from the cited clinical literature and regulatory record.

• Narrow approved indication. FDA approval is limited to HIV-associated lipodystrophy. All other uses — general visceral-fat reduction, anti-aging, cognitive enhancement, non-HIV NAFLD or MASH — are off-label and unsupported by large controlled trials ^[14].
• Non-HIV population generalizability. Pivotal trials were in HIV-positive adults on antiretroviral therapy. Mechanistic extrapolation to non-HIV populations is plausible, but has not been established by large RCTs in those groups ^[13].
• Visceral fat reaccumulation. VAT returns within weeks of stopping; benefits require continued dosing ^[17].
• IGF-1 elevation and oncologic caution. GH-axis stimulation raises serum IGF-1. Trials showed no excess malignancy signal over 52 weeks, but active malignancy is a labeled contraindication and long-term oncologic safety data are limited ^[14].
• Glucose monitoring. Modest glucose perturbation can occur; monitoring is warranted in individuals with prediabetes or dysglycemia ^[16].
• WADA prohibition. Tesamorelin is a GHRH analogue prohibited in sport under WADA Prohibited List S2 (peptide hormones, growth factors, related substances and mimetics), in- and out-of-competition.
• Research-grade supply. Research-grade material lacks the pharmaceutical-grade purity and potency oversight of the approved product ^[13].

Where it fits in metabolic research

Tesamorelin is the desk's anchor in regulatory reality. Unlike retatrutide — still in Phase 3 — or MOTS-c — still entirely preclinical — tesamorelin has a completed approval pathway, labeled indication, and a 2026 meta-analysis confirming its efficacy across five RCTs ^[13]. Its place on this desk is as a reference point: what a peptide-based metabolic intervention looks like when it has cleared the full clinical-trial and regulatory review process, including the constraints that come with it — a narrow indication, ongoing monitoring requirements, and a clearly stated reaccumulation effect. See how it lines up on the comparison page.