Tesamorelin: The Approved End of the GH-Axis Spectrum

The short version

Tesamorelin is a synthetic 44-amino-acid peptide — the full length of human GHRH — modified only at the N-terminus, where a trans-3-hexenoic acid group blocks the enzyme (DPP-IV) that would otherwise clip it within minutes. In healthy men, two weeks of daily dosing raised overnight GH by a statistically significant margin and IGF-1 by 181 micrograms per liter, without affecting insulin sensitivity ^[15].

It is the only compound on this desk with an FDA-approved indication. In November 2010, the FDA approved tesamorelin under NDA 022505 to reduce excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy — a specific metabolic complication of long-term HIV treatment. A 2026 meta-analysis of five RCTs confirmed the core findings: visceral adipose tissue down by a mean of 27.71 cm², trunk fat down 1.18 kg, hepatic fat fraction down 4.28%, and lean mass up 1.42 kg, without serious adverse events ^[12].

Outside that approved indication, tesamorelin has no cleared human use. This page describes the approved indication in clinical terms and the off-label research in research terms; it recommends no dose.

What it is

Tesamorelin acetate is a synthetic analog of GHRH(1-44)-NH2 — the full 44-amino-acid sequence of natural human GHRH, amidated at the C-terminus — bearing a trans-3-hexenoic acid conjugated to the N-terminal tyrosine. The N-terminal modification confers resistance to DPP-IV cleavage, extending plasma stability well beyond the two-minute half-life of native GHRH. Its empirical formula (free base) is C221H366N72O67S; it is supplied as the acetate salt.

You will also see it under the research code TH9507, or described as a "GHRH(1-44) analogue" or "growth hormone-releasing factor analogue." The approved drug product was a branded prescription medication for a specific HIV indication. Research-grade material sold outside that indication is not the approved product and lacks the purity, potency and oversight controls of the clinical formulation. All trademarks for the branded prescription product are avoided on this site.

How it works

Tesamorelin binds the GHRH receptor on anterior-pituitary somatotroph cells and activates the Gs/adenylyl cyclase/cAMP/PKA cascade, stimulating pulsatile endogenous GH synthesis and secretion. The resulting GH pulse drives hepatic production of IGF-1, which together with GH promotes lipolysis — the breakdown of stored fat — preferentially in visceral adipose tissue (fat stored around abdominal organs).

Because it amplifies the body's own pulsatile GH rhythm rather than supplying exogenous GH, its metabolic profile differs from recombinant GH: the normal physiologic feedback from somatostatin and IGF-1 remains operative, which is the likely explanation for why tesamorelin does not produce the acromegaly-like side-effect profile of exogenous GH at the doses studied ^[15]. The mechanism that made it useful in HIV lipodystrophy — visceral-fat reduction — is also the hypothesis behind off-label research in non-HIV abdominal fat, hepatic steatosis, and, separately, cognitive function in aging ^[8].

What the research shows

Meta-analytic summary (approved indication). A 2026 meta-analysis of five RCTs in HIV-associated lipodystrophy found tesamorelin reduced visceral adipose tissue by a mean of 27.71 cm² (95% CI −38.37 to −17.06; P<0.001), trunk fat by 1.18 kg, and hepatic fat fraction by 4.28%, while increasing lean body mass by 1.42 kg. No serious adverse events were reported in any of the pooled trials ^[12].

Pivotal JAMA RCT. In 50 antiretroviral-treated HIV adults (28 on tesamorelin, 22 on placebo), tesamorelin 2 mg/day produced a treatment effect of −42 cm² in visceral fat (P=0.005) and reduced hepatic lipid-to-water percentage by a net −2.9% (P=0.003) over six months ^[14].

52-week extension. The longer-term program (tesamorelin 2 mg/day, n=273 vs placebo n=137) found visceral fat reduction sustained at −18% over 52 weeks (P<0.001 vs baseline). Visceral fat reaccumulated upon discontinuation, and changes in glucose parameters over 52 weeks were not clinically significant — an important safety signal ^[16].

GH pulsatility and insulin sensitivity in healthy men. In 13 healthy men, 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), while neither fasting glucose (P=0.93) nor insulin-stimulated glucose uptake (P=0.61) was significantly affected — demonstrating that short-term GH-axis stimulation at this level did not impair insulin sensitivity ^[15].

Cognition in older adults (GHRH-analog class data). A 2012 RCT in 152 older adults (including 66 with mild cognitive impairment) using daily subcutaneous GHRH-analog stimulation found a favorable effect on cognition (P=0.03), with a specific executive-function benefit (P=0.005), alongside IGF-1 +117% and body fat −7.4% ^[8]. These results are from the tesamorelin-class study most cited in the GH-axis cognition literature.

Liver safety. The NIH LiverTox monograph assigns tesamorelin a likelihood-of-liver-injury score of E (unlikely hepatotoxin), noting no cases of attributable liver injury and no de novo serum-enzyme elevations in trials ^[13].

Reported effects, cautions and safety

The cautions for tesamorelin follow directly from its evidence base:

• Approval is indication-specific. FDA approval covers only HIV-associated lipodystrophy in adults. All other uses — general visceral-fat reduction, non-HIV NAFLD, cognitive enhancement, anti-aging — are off-label and investigational ^[13].
• Visceral fat reaccumulates on discontinuation. Benefits require continued dosing; cessation within weeks reverses the effect ^[16].
• Long-term oncologic data are limited. GH-axis stimulation raises IGF-1, a growth factor. While the 52-week trial showed no excess malignancy signal, long-term oncologic safety is limited; active malignancy is a labeled contraindication ^[16].
• Glucose monitoring in at-risk individuals. Modest glucose perturbation can occur; those with prediabetes or dysglycemia warrant monitoring, though the dedicated type-2-diabetes trial found no significant HbA1c change ^[16].
• Research-grade vs. approved drug. Research-grade tesamorelin sold for laboratory use lacks the purity and potency controls of the prescription product and is not approved for self-administration outside the licensed indication ^[13].
• WADA prohibition. Tesamorelin is prohibited in sport as a GHRH analog under the WADA Prohibited List (S2: peptide hormones, growth factors, related substances and mimetics), in- and out-of-competition ^[1].

Where it fits in GH-axis research

Tesamorelin is the highest-evidence compound on this desk, by the straightforward measure of randomized controlled trials in humans. Where CJC-1295 has early pharmacokinetic data and Sermorelin has a pediatric approval and a 2008 editorial caution, tesamorelin has meta-analyzed RCTs ^[12] and an FDA approval, limited to one specific population. Its story illustrates what full development of a GHRH analog looks like: decades of trial data, a narrow approved indication, and a wide field of off-label questions that the approved evidence does not directly answer. See how the three analogs compare on the comparison page.