Tesamorelin vs ipamorelin: a licensed GHRH analogue against a ghrelin mimetic

Three things separate these peptides: the receptor they use, their size, and the weight of evidence behind them. Tesamorelin is a 44-amino-acid hormone analogue acting on the GHRH receptor. Ipamorelin is a five-amino-acid molecule acting on the ghrelin receptor. Tesamorelin has a US prescribing label built on randomised trials in more than 800 people; ipamorelin has a hospital pharmacokinetic study and a phase 2 trial.

Both raise growth hormone (GH) in people, and that is the main thing they have in common. They have never been compared with each other in a trial. Each has a full profile on the site: see the tesamorelin guide and the ipamorelin guide.

Tesamorelin copies GHRH, the hypothalamic hormone that tells pituitary somatotrophs to make and release GH. Its prescribing information reports that, in laboratory tests, it activates the human GHRH receptor about as potently as the native hormone, and that it raises IGF-1 and IGFBP-3 ^[1]. Ipamorelin copies ghrelin instead. It activates GHS-R1a, a receptor cloned in 1996 as the target of synthetic GH secretagogues ^[19], and its GH-releasing effect in rat pituitary cells was blocked by GHRP antagonists but not by GHRH antagonists ^[7].

Both were described as selective for GH, but the evidence differs in kind. For tesamorelin, trial patients showed no clinically meaningful shifts in thyroid-stimulating hormone, LH, ACTH or prolactin, according to the label ^[1]. For ipamorelin, the finding comes from pigs: ACTH and cortisol stayed flat at over 200-fold its GH-releasing ED50, whereas GHRP-2 and GHRP-6 raised both ^[7]. One is a human trial observation; the other has not been confirmed in people.

Because the two pathways are separate, combining them can release more GH than either alone. That was shown in healthy men given a GH-releasing hexapeptide together with GHRH ^[11], not with these two peptides.

Despite its stabilising cap, tesamorelin is cleared quickly. In healthy volunteers, half of a subcutaneous Egrifta WR dose was eliminated in about 11 minutes on average, and less than 4% of a 2 mg injection of the original formulation reached the circulation, according to the label ^[1]. It is still given once a day, and its effects on IGF-1 build over weeks: in the first phase 3 trial, IGF-1 was 81% higher than baseline at 26 weeks ^[2].

Ipamorelin circulates longer. Infused intravenously over 15 minutes in healthy men, it had a terminal half-life near two hours, and GH rose once, topping out around 40 minutes in, before falling away ^[8]. No published study reports ipamorelin’s effect on IGF-1 over weeks of use in people.

The two pivotal trials enrolled people with HIV on antiretroviral therapy who had excess abdominal fat. In the first, 412 patients were randomised to 2 mg daily or placebo; after 26 weeks visceral fat measured by CT had fallen 15.2% with tesamorelin and risen 5.0% with placebo, and triglycerides fell ^[2]. Pooled across both trials, 806 patients, the treatment effect on visceral fat was -15.4%, with no significant change in fat under the skin ^[3]. Continued treatment held the reduction for 52 weeks, and the fat reaccumulated once it stopped ^[4].

Smaller randomised trials extend the picture. In 50 people with HIV, six months of 2 mg daily reduced both visceral and liver fat compared with placebo; fasting glucose rose at two weeks but the difference was not significant at six months ^[5]. In 152 adults aged 55 to 87, 1 mg nightly for 20 weeks had a favourable effect on a cognitive composite, raised IGF-1 by 117% and cut body fat by 7.4% ^[6]. In 53 people with type 2 diabetes, 12 weeks of 1 or 2 mg daily did not change insulin response, fasting glucose or HbA1c compared with placebo ^[17].

Ipamorelin’s one efficacy trial in people targeted post-operative ileus, the slowdown of the gut after abdominal surgery. In 117 adults after bowel resection, intravenous ipamorelin 0.03 mg/kg twice daily for up to seven days was well tolerated, but the median wait until patients could manage a solid meal, 25.3 hours with ipamorelin and 32.6 hours with placebo, was not a statistically significant difference ^[9].

The rest of its research is in animals. In adult female rats injected three times a day for 15 days at 18 to 450 µg a day, ipamorelin increased the rate of bone growth and body-weight gain in a dose-dependent way without changing total IGF-1 ^[10]. These results show biological activity in rats, not a benefit in people, and animal doses are not converted to human ones here.

This is where the two differ most. Tesamorelin has randomised evidence that it reduces visceral fat, the fat around the organs, in people with HIV-associated fat gain ^[2][3]. Even so, its label rules it out for weight loss management, describing its effect on body weight as neutral, and says its long-term effect on the heart and circulation is unknown ^[1]. Its benefit is a shift in where fat sits, in a specific patient group, for as long as treatment continues.

Ipamorelin has no human data on fat, weight or body composition at all. As a ghrelin-receptor agonist it may also raise appetite: GHRP-2, which acts on the same receptor, increased food intake by about 36% in healthy men during an infusion ^[12]. That has not been measured for ipamorelin in people.

Tesamorelin trials used 2 mg injected under the skin once a day ^[2][3][5], and the cognition trial used 1 mg nightly ^[6]. For the marketed Egrifta WR vial the labelled amount is 1.28 mg a day, given into the skin of the abdomen; the label warns that Egrifta SV uses a different dose and the two cannot be swapped ^[1].

Ipamorelin’s human doses were intravenous: infusions of 4.21 to 140.45 nmol/kg in the pharmacokinetic study ^[8] and 0.03 mg/kg twice daily in the surgical trial ^[9]. No subcutaneous human dose has been set by a published trial. All of these figures describe research and labelling, not recommendations; our peptide calculator covers unit arithmetic, and our guide to bacteriostatic water covers mixing.

Six reactions affected more than 5% of patients in the licensed-product trials: arthralgia, redness and itching where the needle went in, pain in the arms or legs, peripheral oedema and myalgia. Over the first 26 weeks a quarter of tesamorelin patients had an injection-site reaction, against 14% given placebo, and an HbA1c at or above 6.5% appeared in 5% compared with 1%. Warnings cover fluid retention, persistently raised IGF-1, allergic reactions and a possible effect on existing tumours; active cancer and pregnancy rule it out ^[1].

Ipamorelin’s human safety data are limited to short intravenous courses. In the surgical trial, adverse events were slightly less frequent with ipamorelin than with placebo (87.5% vs 94.8%) ^[9], a figure that says more about recovering from bowel surgery than about the drug. A 2026 GH-axis review groups the risks for these agents under endocrine and metabolic disturbance, fluid retention, musculoskeletal pain and injection-site problems ^[13].

Because tesamorelin and ipamorelin use different receptors, the pairing follows the same logic as CJC-1295 and ipamorelin: a GHRH signal plus a ghrelin-receptor signal. The supporting evidence is indirect, from older compounds in healthy men ^[11]. No published study has given tesamorelin with ipamorelin, and none has measured the effects, side effects or timing of the combination.

Search data shows strong interest in a tesamorelin ipamorelin blend, with product-style names such as “2x blend tesamorelin / ipamorelin” and three-peptide mixes that add MGF or Mod GRF 1-29. None of those formulas comes from a clinical study, and no tesamorelin ipamorelin dosage has been tested. Tesamorelin’s licensed dose and safety data apply to the licensed product used alone ^[1].

Comparing tesamorelin with the CJC-1295 and ipamorelin pairing means comparing one licensed GHRH analogue with an unlicensed GHRH analogue plus a ghrelin mimetic. The evidence gap runs one way: tesamorelin has outcome trials, while CJC-1295 has phase 1 hormone studies of its DAC form and nothing for the no-DAC form used in most blends. No trial has compared them.

The third name in this search is sermorelin, the 29-amino-acid GHRH fragment once licensed as Geref. It shares tesamorelin’s receptor and ipamorelin’s lack of a current licence. Our pages on tesamorelin vs sermorelin and ipamorelin vs sermorelin set out those comparisons.

Tesamorelin is a prescription medicine in the US ^[1]; the research-grade vials sold online are not that licensed product. Ipamorelin has no licence anywhere in our markets. In the US, ipamorelin acetate was among compounding substances the FDA still flagged in April 2026 as potentially carrying significant safety risks ^[15]. In Australia, the June 2026 Poisons Standard lists ipamorelin as a Schedule 4 poison that is also subject to the Appendix D restrictions on possession; tesamorelin is not named, though it may fall within the class entry for GHRH analogues ^[18]. In New Zealand, Medsafe lists both as prescription medicines ^[16]. More detail is on our legal status overview and Australian legal status page. Both peptides are banned in sport at all times ^[14].

A 44-amino-acid peptide and a five-amino-acid one are priced on different scales, so compare tesamorelin prices and ipamorelin prices per milligram rather than per vial. For a premixed vial, the certificate of analysis should identify and quantify both peptides separately. Reading the mass and purity lines is covered in our COA guide, and our list of third-party tested suppliers shows who pays for outside testing.