These two get compared because both are sold online as growth-hormone peptides. Their records barely overlap. Tesamorelin is the active drug in Egrifta, approved by FDA in 2010 for one narrow use [1]. Ipamorelin never got past phase 2, and in 2024 not one of FDA's compounding advisers voted to let pharmacies make it [5].
Different receptors, the same goal of more growth hormone
Tesamorelin is a synthetic analog of growth-hormone-releasing factor, the brain's signal telling the pituitary to release growth hormone [1]. In its main trial, IGF-1, the blood marker of growth-hormone activity, rose 81% on tesamorelin and fell 5% on placebo [7].
Ipamorelin takes the other route. It acts on the ghrelin receptor, and its phase 2 trial describes it as a ghrelin mimetic [10]. In healthy men given it by IV, each dose produced a single growth-hormone pulse, with a half-life of about 2 hours [9].
Neither contains growth hormone. Both rely on a pituitary that still responds. Mechanism is the least important difference between them.
Side by side: an FDA label against a failed trial
| Tesamorelin | Ipamorelin | |
|---|---|---|
| Mechanism | GHRH analog [1] | Ghrelin mimetic [10] |
| FDA status | Approved as Egrifta, November 10, 2010; a biologic since March 23, 2020 [2] | Never approved |
| Labeled use | Excess abdominal fat in adults with HIV and lipodystrophy [1] | None |
| Can a pharmacy compound it? | No: biologics have no 503A or 503B exemption [3] | No: advisers voted 0 yes, 12 no, 1 abstention, October 29, 2024 [5] |
| Largest trial | Phase 3, 412 adults with HIV, 26 weeks [7] | Phase 2, 117 adults after bowel surgery [10] |
| Main result | Visceral fat -15.2% vs +5.0% on placebo | No significant benefit (p = 0.15) |
| Main safety signals | Injection-site reactions, fluid retention, glucose intolerance (label section 5) | 2 deaths (cause unclear), more high blood sugar (FDA review) |
| Sport | Prohibited at all times, WADA S2.2.4 [11] | Prohibited at all times, WADA S2.2.4 [11] |
The tesamorelin trials were run in adults with HIV and were sponsored by its maker, Theratechnologies.
Tesamorelin's record: visceral fat down about 15%, in one population
Tesamorelin's evidence is real but narrow. In the first phase 3 trial, 412 adults with HIV and excess belly fat took it or placebo for 26 weeks. Visceral fat fell 15.2% on the drug and rose 5.0% on placebo [7].
A pooled analysis of two phase 3 trials, 543 people on the drug and 263 on placebo, put the treatment effect at -15.4% at 26 weeks [8]. Fat under the skin barely moved, a -0.6% treatment effect that was not significant. That is a change on a scan in one fat compartment, in people with HIV-related fat gain.
The label sets the limits plainly. Egrifta "is not indicated for weight loss management as it has a weight neutral effect," and its long-term cardiovascular safety "has not been established" [1]. Trials outside HIV exist, such as one in older adults with mild memory problems, but they are single, off-label studies. What they show is covered in does tesamorelin work.
Because it is approved, tesamorelin has an FDA-reviewed safety section. Injection-site reactions occurred in 25% of patients on Egrifta and 14% on placebo over the first 26 weeks. HbA1c reached 6.5% or higher in 5% against 1% [1]. The label also lists fluid retention, a raised IGF-1 to monitor, and a cancer precaution. The full picture is on is tesamorelin safe.
Ipamorelin's record: one dosing study, one trial that missed
Ipamorelin was developed to speed gut recovery after bowel surgery. In the phase 2 trial, median time to a first tolerated solid meal was 25.3 hours on ipamorelin and 32.6 hours on placebo. The difference was not significant (p = 0.15), and no efficacy measure differed significantly [10].
FDA's 2024 review of that trial found two deaths in the ipamorelin group after surgical leaks, and wrote that it is unclear whether they were related to the drug [4]. High blood sugar at discharge ran 14.3% on ipamorelin and 8.6% on placebo. Its only other human data come from a dosing study in healthy men [9].
| Study | Peptide | Who and how many | What it found |
|---|---|---|---|
| Falutz 2007 [7] | Tesamorelin | 412 adults with HIV, randomized | Visceral fat -15.2% vs +5.0%; IGF-1 +81% vs -5% |
| Falutz 2010 [8] | Tesamorelin | 806 adults with HIV, two trials pooled | Treatment effect -15.4% on visceral fat; fat under the skin unchanged |
| Gobburu 1999 [9] | Ipamorelin | Healthy men, 8 per dose level | Single growth-hormone pulse; half-life about 2 hours |
| Beck 2014 [10] | Ipamorelin | 117 adults after bowel surgery, randomized | No significant benefit |
| Head-to-head trial | Both | None published | Unknown |
Why neither can be compounded
Tesamorelin is shut out by its category. On March 23, 2020, protein drugs like Egrifta were moved onto biologics licenses [2]. FDA's notice to compounders said those products "will not be eligible for the exemptions for compounded drugs under sections 503A and 503B" [3]. A pharmacy can't make tesamorelin from bulk powder under either exemption. The status details are on is tesamorelin FDA approved.
Ipamorelin is shut out on the evidence. It has no USP monograph and is in no approved drug, so the 503A bulks list was its only possible route [4]. On October 29, 2024, the committee voted on whether to add it: 0 yes, 12 no, 1 abstention, for the free base and again for the acetate [5]. Outsourcing facilities can't use it either, because FDA keeps it in Category 2 of the 503B list [6].
What a prescriber can offer: Egrifta for its labeled use, or a deficiency workup
If you have HIV and excess belly fat, Egrifta is an approved option, and a prescriber can weigh its label against your history. Outside that use, any prescription is off-label, and the label's own words matter: it is weight neutral, and it is meant to be judged on a measured drop in visceral fat.
If your interest is growth hormone in general, ask your clinician whether testing for growth-hormone deficiency makes sense, and which approved treatments fit if it does. A GHRH peptide that does have a compounding route is compared in tesamorelin vs sermorelin, and the ipamorelin matchup with it is in sermorelin vs ipamorelin. How this site weighs evidence is set out in how we check.