What is tesamorelin?

Tesamorelin is a synthetic 44-amino-acid analogue of growth-hormone-releasing hormone (GHRH), the signal the hypothalamus normally sends to the pituitary gland to trigger growth-hormone (GH) release. It is sold in the United States as Egrifta by Theratechnologies and is the only FDA-approved medicine containing the compound^[1]. Outside the US, there is no authorised tesamorelin product: the European marketing-authorisation application was withdrawn in 2012 after the EMA's Committee for Medicinal Products for Human Use concluded that the data did not support a positive benefit-risk balance^[2]. The UK and EU therefore have no licensed tesamorelin product, and access in those jurisdictions runs only through unlicensed-medicine or named-patient routes on a prescriber's responsibility.

How tesamorelin works

Tesamorelin binds the GHRH receptor on the pituitary gland and stimulates the gland to release the person's own GH in roughly normal pulses^[1]. This is a deliberate design choice: rather than injecting recombinant growth hormone from outside the body, tesamorelin works by amplifying the body's own release pattern. A trans-3-hexenoyl modification at the N-terminus (the starting end of the peptide chain) protects the molecule from rapid breakdown by the enzyme dipeptidyl peptidase-4 (DPP-4), giving it a usable clinical half-life on a once-daily subcutaneous schedule. The downstream effect is a modest, sustained rise in circulating GH and, consequently, insulin-like growth factor 1 (IGF-1), the hormone that mediates most of GH's tissue-level effects.

The GHRH-analogue mechanism places tesamorelin in a class that also includes sermorelin (briefly approved in the US for paediatric GH deficiency but now off the market as an approved drug) and CJC-1295 (not approved anywhere). Tesamorelin is the only member of that class with a current FDA approval.

What tesamorelin is approved for

The FDA approved tesamorelin in November 2010 for one specific indication: reducing excess abdominal fat in adults living with HIV who have developed lipodystrophy, a pattern of abnormal fat accumulation around the abdominal organs caused by the interaction between HIV antiretroviral therapy and the underlying infection^[1]. The approval was supported by two multicentre, double-blind, placebo-controlled Phase 3 trials and a safety extension. The pooled analysis of those trials, published in the Journal of Clinical Endocrinology and Metabolism, enrolled 806 adults on antiretroviral therapy (543 tesamorelin, 263 placebo) and ran for 26 weeks, with a further 26-week safety extension^[3]. At 26 weeks, visceral adipose tissue (VAT) in the tesamorelin group fell by approximately 24 cm2 compared with a 2 cm2 increase in the placebo group, a treatment effect of around 15 percent^[3]. Secondary lipid markers, including triglycerides, also improved.

Tesamorelin is not approved for general body-composition improvement, anti-ageing, athletic performance, or any other indication. Off-label use for those purposes is common in community discussion and in some private clinics, particularly in the United States, but the published trial evidence for those uses is essentially absent: all controlled trial data comes from the HIV-lipodystrophy population on the labelled dose and schedule. See the tesamorelin regulation page for the country-by-country picture.

What the evidence actually shows

The Phase 3 programme is the clearest evidence base the peptide has. VAT reduction was demonstrated and replicated across the two pivotal trials. A secondary analysis found that patients who achieved at least 8 percent VAT reduction also showed meaningful improvements in triglycerides, adiponectin levels, and preservation of glucose homeostasis over 52 weeks^[4]. The metabolic-benefit finding matters because it helps explain why VAT reduction in HIV lipodystrophy is considered clinically meaningful rather than cosmetic.

The safety picture from the trials is well-characterised within the approved indication. The FDA label reports that 47 percent of treated patients had IGF-1 levels greater than two standard deviations above normal at 26 weeks, and 36 percent exceeded three standard deviations^[1]. The most common adverse events were injection-site reactions, arthralgia (joint pain), and peripheral oedema (fluid retention). The label lists active malignancy, disrupted pituitary function (from surgery, irradiation, or tumour), and pregnancy as contraindications. Glucose monitoring is required, particularly in patients with pre-existing glucose dysregulation, because the GH-axis mechanism can affect insulin sensitivity.

What the trials do not address is the safety profile outside the approved indication. The AE picture in healthy adults using tesamorelin off-label has not been characterised in any controlled trial. Long-term data on cancer incidence in non-HIV populations are limited, and that gap matters because sustained IGF-1 elevation is a theoretical oncology concern.

Where tesamorelin sits in the GHRH class

Tesamorelin belongs to the same structural family as CJC-1295 and sermorelin, all of which are built on the first 29 amino acids of native GHRH. Tesamorelin's N-terminal modification gives it DPP-4 resistance without the long albumin-binding half-life that the DAC variant of CJC-1295 relies on. In practice, tesamorelin operates on a once-daily schedule, CJC-1295 without DAC on a similar short-half-life schedule, and CJC-1295 with DAC on a once-weekly or less frequent schedule. None of them should be treated as interchangeable: the pharmacokinetics and the evidence bases differ substantially, and only tesamorelin has a current FDA approval and a characterised trial dataset in humans.

The literature occasionally groups tesamorelin with ipamorelin and other growth-hormone secretagogues in the context of off-label use. The mechanistic overlap is real: all stimulate GH release by different receptor pathways. The evidential overlap is not. Tesamorelin has Phase 3 human trial data in a defined population. Most other agents discussed in the same conversations do not.

Medical disclaimer

This article is educational and does not constitute medical advice. Tesamorelin is a prescription medicine in the United States, approved for a specific indication in HIV-associated lipodystrophy. It is not an authorised medicine in the EU, EEA, or UK. Decisions about whether tesamorelin is appropriate for any individual, on-label or off, belong with a prescribing clinician who knows that person's full medical history. PeptideMethods Editorial Team does not advise on starting, stopping, dosing, or sourcing any medicine.