Tesamorelin vs ipamorelin, and how sermorelin, GHRP-6, hexarelin and MK-677 differ

Evidence limits

What can a comparison of these compounds not show?

The one direct comparison found in the ipamorelin records opened for this page is in animals. In rat pituitary cells, anaesthetised rats and conscious pigs, ipamorelin and GHRP-6 released growth hormone with similar potency; these are animal and cell results with no animal count in the abstract and do not establish a human result, and the study tested GHRP-6 and GHRP-2, not hexarelin, tesamorelin or sermorelin (Raun et al., European Journal of Endocrinology, 1998).

A 2020 review that covers sermorelin, GHRP-2, GHRP-6, ibutamoren and ipamorelin reached the same limit. It describes a 'paucity of data' on their clinical effects, and it ran no new trial (Sinha et al., Translational Andrology and Urology, 2020).

How does tesamorelin differ from ipamorelin?

Tesamorelin and ipamorelin act on different signals and hold different regulatory records. Tesamorelin is an analogue of GHRH, the hypothalamic signal that tells the pituitary to release growth hormone, and its FDA label, revised March 2025, lists an approved indication of excess abdominal fat in adults with HIV and lipodystrophy; the label gives 2010 as the initial US approval year and covers the WR formulation (Egrifta WR label, March 2025). Ipamorelin copies ghrelin, a stomach hormone, and the FDA found in 2024 that no approved drug contains it (FDA briefing document, 29 October 2024). No joint trial of the two compounds was found in the searches of 14 October 2026.

The tesamorelin trial record is larger. In 412 adults with HIV and extra abdominal fat, visceral fat fell by 15.2 percent on tesamorelin and rose by 5.0 percent on placebo over 26 weeks; this is one trial in one patient group and says nothing about ipamorelin (Falutz et al., New England Journal of Medicine, 2007). In the same 412 adults with HIV, IGF-1 rose by 81.0 percent on tesamorelin, a tesamorelin-only result in one patient group (Falutz et al., 2007). In those 412 adults with HIV, adverse events did not differ significantly between the tesamorelin and placebo groups, but more people on tesamorelin withdrew because of one, in one trial of one drug that says nothing about ipamorelin (Falutz et al., 2007).

The ipamorelin trial record is smaller. A Phase 2 trial in 117 enrolled bowel-surgery patients (114 analysed) found no statistically significant difference from placebo in time to first tolerated meal, in one small postoperative trial that cannot show that no difference exists (Beck et al., International Journal of Colorectal Disease, 2014). The ipamorelin study-findings page sets out the full record.

Is ipamorelin or tesamorelin better?

No source opened for this page ranks the two, so none supports calling either one better. The records differ in kind. For one named condition, abdominal fat in HIV-associated lipodystrophy, tesamorelin has a randomised 26-week trial in 412 adults with HIV (Falutz et al., 2007) and an FDA label (Egrifta WR label, March 2025). For ipamorelin, the one trial of a clinical outcome found in the searches of 14 October 2026, in 117 enrolled bowel-surgery patients (114 analysed), showed no statistically significant difference from placebo in one small postoperative trial that cannot show that no difference exists (Beck et al., 2014). The label states that tesamorelin is not indicated for weight loss management, and ipamorelin research material is not a substitute for any approved medicine.

Tesamorelin's label also lists risks. The Egrifta WR label, revised March 2025, lists warnings for neoplasms, raised IGF-1, fluid retention, glucose intolerance, hypersensitivity and increased mortality in acute critical illness, and it states that long-term cardiovascular safety has not been established. The label lists joint pain, reactions where the medicine is given, pain in the limbs, peripheral swelling and muscle pain among its named adverse reactions, and it says its adverse-reaction data come from clinical trials of the earlier tesamorelin formulation (Egrifta WR label, March 2025).

For ipamorelin, the adverse-event sources found for this page include the small surgery trial and the FDA's 2024 review, covered on the ipamorelin side effects page.

How does sermorelin differ from ipamorelin?

Sermorelin is a 29-amino-acid analogue of GHRH and the shortest synthetic peptide with the full biological activity of GHRH (Prakash and Goa, BioDrugs, 1999). Ipamorelin is a five-amino-acid ghrelin mimetic. The US sold sermorelin as GEREF: the FDA approved a vial form in 1997 with an approved indication in children with idiopathic growth hormone deficiency, and an earlier form from 1990 as a test of the pituitary's ability to release growth hormone. The maker notified the FDA of discontinuation of both in 2008, the FDA withdrew approval effective 18 June 2009, and the FDA found on 4 March 2013 that the withdrawal was not for reasons of safety or effectiveness (Federal Register, volume 78, number 42).

The sermorelin record is older and paediatric. A 1999 review covers older studies of sermorelin in children with idiopathic growth hormone deficiency; this page reports none of its outcome figures, and the review says nothing about ipamorelin (Prakash and Goa, 1999).

In Australia the Poisons Standard has an individual Schedule 4 entry for sermorelin, while ipamorelin has Schedule 4 and Appendix D, clause 5 entries (October 2026 instrument, read 14 October 2026). This page does not determine how Appendix D group entries apply to sermorelin; the Australian law hub covers that distinction, and Is ipamorelin legal in Australia? covers the ipamorelin listing.

Is sermorelin or ipamorelin stronger?

No study found for this page compares the strength of sermorelin and ipamorelin, so the question has no sourced answer. Strength depends on the yardstick: how much growth hormone is released, how long the rise lasts, or what the body does afterwards. In eight healthy men at each of five infusion levels, ipamorelin was followed by a single growth hormone peak about 0.67 hours after the infusion and then a fall to negligible levels; the study measured hormone levels only (Gobburu et al., Pharmaceutical Research, 1999). The sermorelin review measured a different outcome, height velocity in children (Prakash and Goa, 1999). A hormone peak and a growth rate cannot be ranked against each other.

A 1998 review of earlier studies covers how secretagogues and GHRH act together, and it ran no new test (Ghigo et al., Annals of Medicine, 1998); this page reports no result from it. It does not rank one compound against the other, and no study opened for this page tested ipamorelin with sermorelin.

How does ipamorelin differ from GHRP-6?

GHRP-6 is an older six-amino-acid peptide that also acts on the ghrelin receptor. In rat pituitary cells, anaesthetised rats and conscious pigs, the two released growth hormone with similar potency and efficacy, and in pigs GHRP-6 raised ACTH and cortisol while ipamorelin did not raise either above the level seen with GHRH; these are animal results with no animal count in the abstract and do not establish a human result (Raun et al., European Journal of Endocrinology, 1998). The FDA lists GHRP-6 in category 2, as a compound that may pose significant safety risks, with concern about effects on cortisol and blood glucose (FDA category 2 page, content current as of 22 April 2026).

Body handling also differed in rats. Ipamorelin cleared from the blood about five times more slowly than GHRP-6 and left mainly in urine, while GHRP-6 left mainly in bile; this is a rat result with no count in the abstract that does not establish a human result (Johansen et al., Xenobiotica, 1998).

The FDA added GHRP-6 to category 2 for the 503B pathway on 29 September 2023, citing immunogenicity risk and 'potential effect on cortisol and increase in blood glucose due to decreases in insulin sensitivity' (FDA category 2 page, content current as of 22 April 2026). Ipamorelin acetate was added on the same date with a different stated reason: immunogenicity, unnatural amino acids and a published study of intravenous ipamorelin in a gastric-motility setting (FDA category 2 page, content current as of 22 April 2026). In the Australian Poisons Standard, GHRP-6 is item 20 and ipamorelin item 25 of Appendix D, clause 5 (read 14 October 2026).

How does hexarelin differ from ipamorelin, and is hexarelin better?

Hexarelin is an older peptide that acts on the ghrelin receptor, and no source opened for this page shows it to be better than ipamorelin. In seven healthy young volunteers, hexarelin raised growth hormone, prolactin, ACTH and cortisol overnight and cut slow-wave sleep; it is a small study of hexarelin alone and is not a comparison with ipamorelin (Frieboes et al., Psychoneuroendocrinology, 2004). The only equivalent measurement for ipamorelin found for this page is the 1998 pig study, with no count in the abstract, in which it did not raise ACTH or cortisol above the GHRH level, an animal result that does not establish a human result (Raun et al., 1998). The species differ, so the contrast is a lead, not a ranking. Human prolactin and cortisol data for ipamorelin were not found.

Another human study shows a limit of the class. In six normal-weight women, within a study of 32 women, hexarelin gave a clear growth hormone rise and then blocked the response to a GHRH test 120 minutes later; this is a small study of hexarelin alone, and no equivalent test of ipamorelin was found (Popovic et al., Clinical Endocrinology, 1997).

Hexarelin is item 22 of Appendix D, clause 5, in the October 2026 Poisons Standard (read 14 October 2026) and is named as examorelin (hexarelin) in the WADA 2026 Prohibited List, S2.2.4.

What are the key differences between ipamorelin and ibutamoren (MK-677)?

Ibutamoren (MK-677) is a non-peptide molecule, while ipamorelin is a five-amino-acid peptide, and both act on the ghrelin receptor. MK-677 has a much longer human trial record: in a trial of 65 healthy adults aged 60 to 81 it raised growth hormone and IGF-1 and increased fat-free mass by 1.1 kg over 12 months against a fall of 0.5 kg on placebo, without any change in strength or function; this is a result for a different molecule and does not transfer to ipamorelin (Nass et al., Annals of Internal Medicine, 2008). The FDA lists ibutamoren in category 2 for a potential congestive heart failure signal, a regulator's flag and not a measured rate (FDA category 2 page, content current as of 22 April 2026).

In the same 65 healthy adults aged 60 to 81 given ibutamoren in the 2-year trial, fasting blood glucose rose by an average of 0.3 mmol/L and insulin sensitivity fell, and the most frequent side effects were more appetite, which eased within a few months, mild swelling of the lower legs and muscle pain; these results belong to MK-677, not ipamorelin (Nass et al., 2008).

On 29 October 2024 the FDA's advisory committee voted 1 yes to 13 no on listing ibutamoren on the 503A compounding list, and 0 yes to 12 no with 1 abstention on ipamorelin; the votes are advice only (FDA final summary minutes). In Australia both appear in Appendix D, clause 5, as items 23 and 25 (October 2026 Poisons Standard, read 14 October 2026).

How do sermorelin, ipamorelin, tesamorelin and hexarelin compare side by side?

Sermorelin and tesamorelin copy GHRH, while ipamorelin and hexarelin copy ghrelin. Of the four, only tesamorelin holds a current FDA approval, and sermorelin's US approvals were withdrawn effective 18 June 2009 after the maker's 2008 discontinuation. No source opened for this page records an approval for ipamorelin or hexarelin. The WADA 2026 list names all four in S2.2.4, prohibited at all times (WADA 2026 Prohibited List). The comparison table below sets out the signal, the regulatory record and the human evidence found for each, and adds GHRP-6 and ibutamoren.

All six compounds belong to one family of growth-hormone releasers, but the records are not equal. The table lists only what the sources opened for this page state, with the date each record was read. A blank in a cell means the sources opened did not report the item, not that the item does not exist. What peptides do in general places the family in the wider field.