Tesamorelin: The Only One of the Three With an Active FDA Approval

The short version

Tesamorelin is a lab-made version of growth hormone-releasing hormone (GHRH) — the full 44-amino-acid signal, not a shortened fragment like sermorelin — with a small chemical modification at one end that makes it resist breakdown in the body and last longer. Like sermorelin, it works by telling the pituitary gland to release the body's own growth hormone (GH), rather than supplying GH directly. The GH that's released then drives the liver to make IGF-1, and together the two hormones promote fat breakdown, with a documented preference for visceral fat — the fat around the internal organs, not just under the skin.

Tesamorelin is the only one of the three compounds on this site with an active FDA approval: it was approved in 2010 specifically to reduce excess abdominal fat in people with HIV-associated lipodystrophy, a fat-redistribution condition linked to antiretroviral therapy. Every other use — general visceral-fat reduction, anti-aging, cognitive support — is off-label and studied only in smaller trials.

This page reports the published findings for its approved use and beyond; it recommends no dose and no use for any individual.

What it is

Tesamorelin is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone — chemically, GHRH(1-44)-NH2 with a trans-3-hexenoic acid group attached to the amino end of the molecule. That N-terminal modification is the whole trick: it makes the peptide resistant to cleavage by the enzyme dipeptidyl peptidase-IV (DPP-IV), which normally breaks native GHRH down quickly, extending tesamorelin's stability in the bloodstream well beyond that of the unmodified hormone. It's also known in the literature by the code name TH9507. Supplied clinically as tesamorelin acetate, its empirical formula (free base) is C221H366N72O67S.

How it works

Tesamorelin binds the growth hormone-releasing hormone receptor (GHRH-R) on the pituitary gland's somatotroph cells, activating the same Gs-protein / adenylyl cyclase / cAMP / PKA signaling cascade that drives natural GHRH signaling. That triggers synthesis and pulsatile release of the body's own growth hormone. The released GH then drives the liver to produce insulin-like growth factor-1 (IGF-1), and GH and IGF-1 together promote lipolysis — fat breakdown — with a documented preference for visceral adipose tissue, the metabolically active fat that surrounds abdominal organs. Because tesamorelin amplifies the body's own pulsatile GH rhythm rather than delivering GH directly, its metabolic profile in the trial record differs meaningfully from that of recombinant growth hormone, particularly on glucose handling.

What the research shows

The strongest current evidence comes from a 2026 meta-analysis pooling five randomized controlled trials in HIV-associated lipodystrophy: tesamorelin reduced visceral adipose tissue by a mean difference of 27.71 cm2 (95% CI -38.37 to -17.06; P<0.001), reduced trunk fat by 1.18 kg, and cut hepatic fat fraction by 4.28 percentage points, while increasing lean body mass by 1.42 kg — all statistically significant, with no serious adverse events reported across the pooled trials ^[6].

That pooled result rests on a run of individual trials going back nearly two decades. The pivotal 26-week Phase 3 trial that led to approval, in 412 HIV patients with abdominal fat accumulation, found tesamorelin 2 mg/day reduced visceral adipose tissue by 15.2% while the placebo group's visceral fat grew by 5.0%; triglycerides fell 50 mg/dL versus a 9 mg/dL rise on placebo, and IGF-1 rose 81.0% ^[11]. The 52-week extension of that program (n=273 on tesamorelin vs. 137 on placebo) found the visceral-fat reduction held at -18% through a full year, but — notably — visceral fat reaccumulated once patients stopped the drug, and changes in glucose parameters over the full year were not clinically significant ^[10]. A separate 6-month JAMA trial in 50 antiretroviral-treated adults found a similar treatment effect: -42 cm2 in visceral fat (P=0.005) and a net -2.9% reduction in hepatic lipid-to-water percentage (P=0.003) ^[8].

In healthy volunteers rather than the approved HIV population, a small 2-week study of 13 healthy men found tesamorelin raised mean overnight GH by 0.5 ug/L (P=0.004) and IGF-1 by 181 ug/L (P<0.0001), while neither fasting glucose nor insulin-stimulated glucose uptake changed significantly — an early signal that short-term use doesn't obviously worsen insulin sensitivity ^[9].

On the regulatory and safety-monograph side, the NIH's LiverTox resource — which tracks drug-induced liver injury — assigns tesamorelin a likelihood score of E, meaning it's an unlikely cause of clinically apparent liver injury; no attributable liver-injury cases and no de novo serum-enzyme elevations were reported across its trials ^[7]. A 2026 structured narrative review of injectable peptides in sports medicine groups tesamorelin alongside CJC-1295 and ipamorelin as a growth-hormone-axis secretagogue that remains investigational outside its approved indication, flagging uncertain safety profiles, product-quality concerns in the unregulated research-chemical market, and near-universal antidoping restrictions ^[12].

Reported effects, cautions & safety

Tesamorelin's research-community reporting is much thinner than sermorelin's or ipamorelin's — likely because tesamorelin, unlike the other two, is an approved prescription drug used mostly under a clinician's supervision for a specific HIV-related indication, rather than a peptide people self-administer for general wellness. There isn't a body of community-reported anecdotal effects available to summarize responsibly here, so this section sticks to what the cited literature and regulatory record establish.

What the evidence review makes clear, framed as open questions rather than settled findings:

• Tesamorelin's FDA approval is narrow — HIV-associated lipodystrophy only. Every other proposed use, including general visceral-fat reduction, anti-aging, and cognitive support, is off-label and investigational.
• The pivotal trials were run in HIV-positive adults on antiretroviral therapy; whether the same effect size holds in people without HIV is mechanistically plausible but not established by large controlled trials.
• Visceral fat reaccumulates within weeks of stopping the drug — the benefit is contingent on continued dosing, not a one-time correction ^[10].
• Because tesamorelin raises circulating IGF-1, a known growth factor, there's a theoretical oncologic-safety question; trials through 52 weeks showed no excess malignancy signal, but long-term data beyond that window are limited, and active malignancy is a labeled contraindication.
• Modest glucose changes can occur, and monitoring is reasonable for people with prediabetes or dysglycemia, though a dedicated type-2-diabetes trial found no significant change in HbA1c.
• Cognitive findings are mixed across the broader GHRH-analog literature: the non-HIV aging trial referenced on the sermorelin page showed an executive-function benefit for a GHRH analog, but a 2025 HIV-specific cognition trial did not find significant neurocognitive improvement over standard care.
• Tesamorelin is prohibited in sport under the WADA Prohibited List (category S2), in- and out-of-competition, as a GHRH analogue.
• The approved pharmaceutical product is expensive and injection-only, which limits access; research-grade material sold outside that supply chain lacks the purity and potency oversight the approved product carries.

Where it fits in the Growth Hormone Axis

Tesamorelin is the heavyweight on this list in a literal sense — the lead compound for this site, and the only one of the three with FDA-reviewed evidence sitting behind an approved indication. Where sermorelin is the physiologic template using a short natural GHRH fragment, tesamorelin is the same GHRH-receptor mechanism re-engineered with a stability-conferring side chain for a longer, more clinically dosed profile. Ipamorelin sits apart mechanistically, working the ghrelin receptor rather than the GHRH receptor, and is frequently studied in combination with a GHRH analog like tesamorelin rather than as a substitute. See the comparison page for how the evidence bases actually stack up.