Tesamorelin vs Sermorelin vs Ipamorelin: Two Receptors, Three Regulatory Stories

Tesamorelin, sermorelin and ipamorelin are shelved together and compared on price per milligram. On the axes that actually separate them they are not comparable at all. Two of the three act at one receptor and the third acts at a different one; their masses span a factor of seven; and their US regulatory histories are three genuinely different stories. No trial has ever compared them head to head, so every ranking published online is an inference from separate studies in different populations.

This guide covers which receptor each compound addresses, what each one's regulatory record actually says in 2026, what the published trials measured, why a milligram comparison across the three is meaningless, and how a certificate for each should be read. It is written for laboratory and in-vitro research procurement. It reports what published studies recorded because that is the public evidence base, and it contains no dosing, administration or human-use guidance, and none should be inferred.

The Two Receptors

Growth hormone release from the pituitary can be stimulated through two distinct receptors, and that is the line these three compounds fall on either side of.

The GHRH receptor is addressed by growth hormone-releasing hormone itself and by fragments and analogues of it. Sermorelin is GRF(1-29) amide, which is literally the first 29 residues of human GHRH with a C-terminal amide. Tesamorelin is a modified GRF(1-44) amide, the full 44-residue hormone carrying a trans-3-hexenoyl group on the N-terminus that protects it from dipeptidyl peptidase-4 cleavage. Both are the natural hormone or a hardened version of it.

GHS-R1a is a different receptor whose endogenous ligand is ghrelin. Ipamorelin is a five-residue synthetic sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, bearing no resemblance to GHRH, and it acts here.

The consequence is that the three do not form a potency ladder. Two of them are versions of one hormone and the third is a different kind of molecule addressing a different target. Content that ranks all three as mild, moderate and strong has imposed a single scale on compounds that do not share one.

The Three Molecules

Those values agree with PubChem CIDs 16137828, 16132413 and 9831659 respectively.

The mass spread is the part worth dwelling on, because it breaks the comparison everyone makes. Tesamorelin is 7.2 times the mass of ipamorelin. So 10 mg of ipamorelin contains about 7.2 times as many molecules as 10 mg of tesamorelin. Any price-per-milligram comparison across the three is comparing mass of material rather than quantity of compound, and for molecules this different in size that is not an approximation, it is a category error. If a comparison is wanted at all, it has to be done per micromole, and even then it compares quantities of compounds that address different receptors.

Three Regulatory Positions

This is where the three separate most sharply, and where most content is simply wrong.

Tesamorelin holds a US marketing authorization. The original Egrifta was approved in 2010, succeeded by Egrifta SV in 2019 and by Egrifta WR in 2025, the formulation currently rolling out. The product is a prescription drug for a specific indication in people living with HIV, supplied by a named manufacturer against a reviewed submission.

Its Canadian position is different, and this is the kind of asymmetry worth checking rather than assuming. An active-ingredient search of the Health Canada Drug Product Database returns two entries for Egrifta from Theratechnologies Inc., DINs 02423677 and 02438712, and both are recorded as cancelled, one pre-market and one post-market. So the same compound is an approved marketed drug in the United States and has no live authorization in Canada.

Sermorelin held an FDA approval as Geref, used in assessing growth hormone reserve and in pediatric growth hormone deficiency. The manufacturer notified the FDA in 2008 that it was discontinuing the product and requested withdrawal of the application, and the product moved to the FDA's Discontinued Drug Product List. The important detail is in a 2013 Federal Register determination responding to a citizen petition: the FDA concluded that the Geref products were not withdrawn from sale for reasons of safety or effectiveness, and on that basis abbreviated applications for them may still be approved. A discontinuation for commercial reasons is a different fact from a safety withdrawal, and conflating the two misstates the record in the direction that sounds worse.

Ipamorelin has never held an approval in any jurisdiction. Its originating characterisation is a 1998 paper, and the FDA's published summary of compounding safety concerns records that ipamorelin acetate "may pose risk for immunogenicity for certain routes of administration," that it "contains unnatural amino acids, which add to the complexity of peptide characterization," and that a published study identified serious adverse events including a death when it was given intravenously for gastric motility.

Where the 2026 compounding decisions leave them

The US compounding rules moved several times in 2026, and none of the three was swept up in the change that got the attention. On 30 October 2026 HHS published a draft enforcement discretion policy covering 503A compounding with six peptides: BPC-157, Epitalon, KPV, MOTS-c, Semax and TB-500. None of these three appears in it. Tesamorelin needs no such policy, since it is an approved drug; sermorelin is compounded under the separate rules that apply to a substance that was the subject of an approved application; ipamorelin remains in the FDA's published list of substances that may present significant safety risks in compounding.

None of this transfers to research-grade material. An approved drug product is a specific formulation made to a specific standard by a named manufacturer, and a lyophilized research powder of the same compound is not that product and carries no marketing authorization, whatever the active ingredient. The existence of an approved tesamorelin product is not a statement about research-grade tesamorelin.

What the Published Trials Measured

The three compounds have radically different evidence bases, and the asymmetry maps onto the regulatory positions rather than onto any mechanistic ranking.

Tesamorelin has the substantial record, in a defined population. The randomized placebo-controlled work in people with HIV and abdominal fat accumulation includes a trial with a safety extension in the Journal of Acquired Immune Deficiency Syndromes in 2010 (PMID 20101189) and long-term safety and effect data in AIDS in 2008 (PMID 18690162). Subsequent work examined inflammatory markers and visceral adipose reduction (PMID 21516030, PMID 22495074) and fat quality independent of fat quantity (PMID 33756511). A 2026 systematic review and meta-analysis appeared in the Journal of the International Association of Providers of AIDS Care (PMID 42538058), and a trial protocol for tesamorelin as an adjunct to exercise for physical function in HIV was published in BMJ Open in 2026 (PMID 42419889).

Sermorelin has a modest literature oriented toward its diagnostic role. A 1999 review in BioDrugs covers its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency (PMID 18031173), and a 2006 review in Clinical Interventions in Aging discusses adult-onset growth hormone insufficiency (PMID 18046908). It also appears in analytical and anti-doping method papers, including enzymatic and serum stability profiling of GHRP and GHRH-related peptides (PMID 37688464).

Ipamorelin has roughly fifty indexed papers, led by the 1998 characterization in European Journal of Endocrinology (PMID 9849822). Recent coverage is narrative review discussing it among peptides in the context of use outside clinical supervision, including in Frontiers in Endocrinology (PMID 42395176) and JBJS Reviews (PMID 42160466).

The one trial everything else rests on

The pivotal tesamorelin work is Falutz J et al., New England Journal of Medicine 2007, "Metabolic effects of a growth hormone-releasing factor in patients with HIV", a randomised, double-blind, placebo-controlled trial in 412 patients with HIV-associated abdominal fat accumulation. Visceral adipose tissue fell in the treated group and rose slightly on placebo over 26 weeks. That trial and its 52-week extension are the basis of the Egrifta approval, and they are the reason tesamorelin is the only one of the three with an evidence base a regulator accepted.

Two things follow that most comparison pages skip. The population was specific: adults living with HIV and a defined pattern of fat accumulation, not a general population. And the result does not transfer to the other two compounds, which were never tested in it.

What ipamorelin's own human trial found

Ipamorelin has one published efficacy trial in people: a 2014 phase 2 study in 114 patients recovering from bowel resection, testing it for postoperative ileus. The authors reported it was well tolerated and that there were "no significant differences between ipamorelin and placebo in the key and secondary efficacy analyses."

Important note: the tesamorelin trials were conducted in a specific clinical population with an approved product; sermorelin's published work concerns growth hormone deficiency and diagnostic use; and ipamorelin's single efficacy trial did not meet its endpoint. No trial has compared any two of the three directly.

How to Verify a Lot of Each

The three sizes need three different readings of a certificate, which is a useful illustration that there is no single correct way to read one.

Tesamorelin, 44 residues. A long peptide has many ways for synthesis to go wrong, so a chromatographic purity figure is genuinely informative here. The N-terminal hexenoyl group is the feature to confirm: without it the molecule is unmodified GRF(1-44) and a different compound. The mass difference is small relative to 5136 daltons, so this needs a method with adequate resolution, and multiply-charged species are the norm at this mass, so a certificate should state the charge state or method rather than a bare number.

Sermorelin, 29 residues. The questions are whether it is the 1-29 fragment rather than a longer or shorter one, and whether it carries the C-terminal amide. It also contains a single methionine, which is oxidation-labile, so a lot's handling history matters and an oxidized species is a mass spectrometry finding at plus 16 daltons rather than a purity finding.

Ipamorelin, 5 residues. Purity is close to uninformative, because a five-residue peptide has very few ways to go wrong on a chromatogram. Worse, two of its residues are D-isomers, which share mass and nearly share chromatographic behavior with their L counterparts, so the most likely error is invisible to both a purity figure and an ordinary mass spectrum. Identity rests on a chiral method or comparison against a properly characterized reference standard. The reason is set out in what actually proves a peptide sequence, and the compound is covered in full in the ipamorelin guide.

Net peptide content applies to all three. A purity ratio says nothing about how much peptide the vial holds, and all three are supplied as salts that take up water, which is the subject of chain length and counterion.

Check the three things that make a certificate checkable:

1. The laboratory is named, with its report number.
2. The lot number on the document matches the vial in your hand.
3. The laboratory publishes a verification page where the report number can be looked up independently.

A certificate that names no laboratory, or whose lot number matches nothing on the container, is a document about some other material. Volta publishes its certificates as page images in its published certificate archive with the issuing laboratory's own verification link, and a certificate for the batch you receive is available on request. Those reports carry both HPLC and mass spectrometry results.

The Combination Vials

Volta stocks all three as single compounds: tesamorelin at 10 mg and 20 mg, sermorelin at 5 mg and 10 mg, and ipamorelin at 5 mg and 10 mg. It also stocks multi-component vials pairing a GHRH analogue with ipamorelin, including tesamorelin combinations at 10 mg and 20 mg and a CJC-1295 no-DAC combination at 10 mg. The fourth member of the GHRH family, CJC-1295, is covered in CJC-1295 DAC vs no DAC.

Those vials are where the two-receptor distinction becomes concrete: each contains one compound addressing the GHRH receptor and one addressing GHS-R1a. A composition certificate for such a vial measures each compound separately, reporting a purity and a net peptide content per component and no single purity for the vial, because the vial is not one substance. This is covered in detail in the analytical tradeoffs of a blend. The label's total milligram figure is divided between the two, so neither compound's quantity is the headline number, and the per-component masses are on the certificate rather than the label.

Given the mass spread, the division is more lopsided in molar terms than the milligram split suggests: in a vial pairing tesamorelin with ipamorelin, equal masses would mean about 7.2 times as many ipamorelin molecules as tesamorelin molecules.

Frequently Asked Questions

What is the difference between tesamorelin and sermorelin?

Both are GHRH analogues acting at the same receptor, but tesamorelin is a modified 44-residue version carrying an N-terminal group that resists enzymatic cleavage, and sermorelin is the plain first 29 residues of the hormone. Tesamorelin is an approved US drug for a specific HIV-associated indication; sermorelin's approval as Geref was discontinued in 2008.

Is tesamorelin better than sermorelin?

No trial has compared them. Tesamorelin has a large randomised trial programme in one specific population and a current approval; sermorelin's published work is older and oriented to growth hormone deficiency and diagnostic use. That is a difference in evidence base, not a measured difference in effect.

What is the difference between sermorelin and ipamorelin?

They act at different receptors. Sermorelin is a GHRH analogue acting at the GHRH receptor; ipamorelin is a five-residue synthetic peptide acting at the ghrelin receptor, GHS-R1a. They are not two versions of one thing.

What is the difference between tesamorelin and ipamorelin?

Tesamorelin is a 44-residue GHRH analogue and an approved drug; ipamorelin is a 5-residue ghrelin-receptor agonist that has never been approved and whose one efficacy trial was negative. They differ in receptor, in size by a factor of 7.2, and in regulatory status.

Can you switch from sermorelin to tesamorelin?

That is a clinical question about prescription medicines, not something this page can answer. What can be said factually is that the two act at the same receptor but are different molecules with different approval histories, and that no trial has studied a transition between them.

Do tesamorelin, sermorelin and ipamorelin work the same way?

No. Tesamorelin is a modified GRF(1-44) amide and sermorelin is GRF(1-29) amide, both acting at the GHRH receptor. Ipamorelin is an unrelated five-residue synthetic peptide acting at GHS-R1a, the ghrelin receptor. They do not form a potency ladder.

Which of the three is FDA-approved?

Tesamorelin holds a current US marketing authorization as Egrifta, first approved in 2010 with the present formulation approved in 2025. Sermorelin held an approval as Geref that was discontinued in 2008. Ipamorelin has never been approved anywhere. None of that applies to research-grade material of any of them.

Was sermorelin withdrawn for safety reasons?

No. The manufacturer requested withdrawal in 2008 and the product moved to the FDA's Discontinued Drug Product List. A 2013 Federal Register determination concluded the Geref products were not withdrawn from sale for reasons of safety or effectiveness, which is why abbreviated applications for them remain possible.

Is tesamorelin approved in Canada?

Not currently. The Health Canada Drug Product Database carries two Egrifta entries from Theratechnologies Inc., DINs 02423677 and 02438712, both recorded as cancelled. So the compound is an approved marketed drug in the United States with no live Canadian authorization.

Has any trial compared the three directly?

No. There is no published head-to-head trial of any two of them. Every comparison, including this one, is assembled from separate studies run in different populations with different endpoints.

Can I compare the three on price per milligram?

Not meaningfully. Their average masses are 5136, 3357.9 and 711.9 g/mol, so a milligram of ipamorelin contains about 7.2 times as many molecules as a milligram of tesamorelin. A mass-based comparison across them compares quantities of material rather than quantities of compound, and they address different receptors in any case.

Why is a purity figure less useful for ipamorelin?

A five-residue peptide has very few ways to produce the truncation and deletion impurities a chromatogram detects, so high purity is easy to achieve and distinguishes little. Two of its residues are also D-isomers, which a standard column and an ordinary mass spectrum cannot separate from their L counterparts.

Sources

• PubChem Compound Summaries, CID 16137828 (Tesamorelin), CID 16132413 (Sermorelin), CID 9831659 (Ipamorelin). National Library of Medicine. CAS numbers, formulas, average masses and monoisotopic masses as cited above.
• Health Canada Drug Product Database, active-ingredient search for tesamorelin: two EGRIFTA entries (Theratechnologies Inc.), DINs 02423677 and 02438712, both recorded as cancelled; searches for sermorelin and ipamorelin returned no result. Checked 6 November 2026.
• US Food and Drug Administration, Federal Register determination, 4 March 2013 (78 FR 42), concerning GEREF (sermorelin acetate): products not withdrawn from sale for reasons of safety or effectiveness.
• Falutz J, Allas S, Blot K, et al. "Metabolic effects of a growth hormone-releasing factor in patients with HIV." New England Journal of Medicine. 2007;357(23):2359-2370. PMID 18057338.
• Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. "Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients." Int J Colorectal Dis. 2014;29(12):1527-1534. PMID 25331030.
• US Food and Drug Administration. "Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks." Content current as of 22 April 2026.
• US Department of Health and Human Services. "Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances." Federal Register, 30 October 2026, FR Doc. 2026-22192.
• Falutz J et al. Journal of Acquired Immune Deficiency Syndromes. 2010. "Effects of tesamorelin, a growth hormone-releasing factor, in HIV-infected patients with abdominal fat accumulation: a randomized placebo-controlled trial with a safety extension." PMID 20101189.
• Falutz J et al. AIDS. 2008. "Long-term safety and effects of tesamorelin, a growth hormone-releasing factor analogue, in HIV patients with abdominal fat accumulation." PMID 18690162.
• Journal of the International Association of Providers of AIDS Care. 2026. "Efficacy and Safety of Tesamorelin in People Living With HIV (PLWH) With Lipodystrophy: A Systematic Review and Meta-Analysis." PMID 42538058.
• BMJ Open. 2026. "Tesamorelin as an Adjunct to Exercise for Improving Physical Function in HIV (TRIUMPH): a clinical trial protocol." PMID 42419889.
• BioDrugs. 1999. "Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency." PMID 18031173.
• Clinical Interventions in Aging. 2006. "Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?" PMID 18046908.
• Raun K et al. European Journal of Endocrinology. 1998. "Ipamorelin, the first selective growth hormone secretagogue." PMID 9849822.
• Biomedical Chromatography. 2023. "In-house standards derived from doping peptides: Enzymatic and serum stability and degradation profile of GHRP and GHRH-related peptides." PMID 37688464.