Tesamorelin and sermorelin are often sold side by side as two strengths of the same idea, and chemically that is close to true. Their regulatory histories do not overlap at all. Each was approved for a different patient, tested against a different endpoint, and each sits in a different corner of federal law today. Nobody has put the two in the same trial. This page sets out the record side by side; it reports research and regulation and gives no usage guidance, per our editorial standards. The individual entries, tesamorelin and sermorelin, carry the depth on each.
Same hormone, cut differently
Both copy growth-hormone-releasing hormone (GHRH), the hypothalamic signal that tells the pituitary to release growth hormone. The difference is how much of the hormone each keeps and whether it is protected:
| Sermorelin | Tesamorelin | |
|---|---|---|
| Length | 29 amino acids (GHRH 1-29) | 44 amino acids (full GHRH) |
| Modification | None | Hexenoyl (C6) chain on the first amino acid |
| Molecular weight | ~3.4 kDa | 5,135.9 Da (label, free base) |
| Label half-life | No current label | 8 minutes (Egrifta SV label, healthy adults) |
| Bioavailability under the skin | Not on a current label | Under 4% (Egrifta label, 2 mg dose) |
The hexenoyl chain was added to protect tesamorelin from the enzyme that breaks GHRH down. Even so, its own label reports an 8-minute elimination half-life and less than 4% absolute bioavailability from a subcutaneous injection. Both molecules act in short pulses, and neither stays in the body for long.
Two approval histories that never met
| Sermorelin (Geref) | Tesamorelin (Egrifta) | |
|---|---|---|
| Sponsor | EMD Serono | Theratechnologies |
| Approved | NDA 019863, 28 Dec 1990; NDA 020443, 26 Sep 1997 | 10 Nov 2010, new molecular entity |
| Approved for | Diagnosing pituitary growth-hormone reserve; growth in GH-deficient children | Reducing excess abdominal fat in HIV-infected adults with lipodystrophy |
| Status today | Both discontinued, "not discontinued or withdrawn for safety or effectiveness reasons" (Federal Register determination) | On the market (Egrifta SV, Egrifta WR) |
| Application type now | Drug (NDA) | Biologic (BLA 022505) |
Sermorelin is the rare compound in this market that was approved, and approved twice. Tesamorelin is the only GHRH analogue approved today. Neither approval had anything to do with building muscle in adults.
Why one became a biologic: the 40-amino-acid line
FDA's database lists Egrifta under BLA 022505, the same number it was approved under in 2010 with a biologics prefix. The reason is size. Federal rules define a protein as "any alpha amino acid polymer with a specific, defined sequence that is greater than 40 amino acids in size" (21 CFR 600.3). The Biologics Price Competition and Innovation Act, enacted in March 2010, provided that an approved drug application for such a product "shall be deemed to be a license" under the Public Health Service Act ten years after enactment, which was March 2020 (42 U.S.C. 262, statutory note).
At 44 amino acids tesamorelin is a protein under that definition; at 29, sermorelin is a peptide and stays a drug. Nothing about either molecule changed. What moved was the legal box, and with it the rules for future generic or biosimilar copies.
What each trial actually measured
The two compounds were never tested on the same endpoint, so their results cannot be read against each other:
| Sermorelin | Tesamorelin | |
|---|---|---|
| Pivotal population | 110 previously untreated, prepubertal GH-deficient children (86 in the efficacy analysis) | 412 (Study 1) and 404 (Study 2) HIV-infected adults with lipodystrophy and excess abdominal fat |
| Design | Open-label, one year, no placebo | Randomised, double-blind, placebo-controlled, 26 weeks + 26-week extension |
| Amount | 30 µg/kg once daily at bedtime, under the skin | 2 mg daily, under the skin |
| Primary measure | Height velocity: 4.1 cm/yr at baseline → 8.0 at 6 months → 7.2 at 12 months | Percent change in visceral fat by CT scan at L4–L5 |
| Source | Thorner 1996, PMID 8772599 | Egrifta WR label, section 14 (openFDA, effective 2026-07-29) |
Sermorelin's evidence is about making short children grow, and it showed that a once-a-day injection could roughly double height velocity in the first months in children whose pituitaries still responded. Tesamorelin's evidence is about moving fat out of the abdomen in a specific adult population. Its pooled lean-mass effect is covered on the tesamorelin entry, and its label calls it weight-neutral. The idea that one is "stronger" than the other in lifters rests on no trial at all.
The census: twelve papers, no comparison
PubMed, 2026-09-30. Tesamorelin returns 94 records; sermorelin (or GHRH 1-29) returns 198. Records naming both: 12. Read by type:
- 3 reviews (2026), on performance-enhancing peptides and on peptides in orthopaedics and sports medicine.
- 9 anti-doping method papers (2015–2026), developing urine and blood tests that detect GHRH analogues, both of these among them.
- 0 clinical comparisons.
ClinicalTrials.gov, 2026-09-30: 24 registrations list tesamorelin as an intervention and 27 list sermorelin. None tests one against the other.
The papers that put these two names together most often are the ones written to catch athletes using them. That is the same pattern found when ipamorelin was compared with each of them: every paper naming ipamorelin and sermorelin, or tesamorelin and ipamorelin, is a review.
Status in sport
WADA's 2026 Prohibited List names both compounds by name in section S2.2.4, "growth hormone releasing factors": "growth hormone-releasing hormone (GHRH) and its analogues (e.g. CJC-1293, CJC-1295, sermorelin and tesamorelin)", prohibited at all times. The detection papers above are the practical side of that listing. The compound-by-compound map is on WADA status by compound, and the wider class is on growth-hormone secretagogues.
Where the dose question is covered
This page leaves dose tables out on purpose. Peptifact's tesamorelin and sermorelin dosage page and Medibact Guides' tesamorelin vs sermorelin dosing comparison set out the label and trial figures and the arithmetic.
The honest summary
- Same hormone, different lengths: sermorelin 29 amino acids, unmodified; tesamorelin 44 plus a hexenoyl chain.
- Sermorelin: approved 1990 and 1997 for children's growth and diagnosis; both discontinued, not for safety or effectiveness.
- Tesamorelin: approved 2010 for abdominal fat in HIV lipodystrophy; a biologic since 2020 because it is longer than 40 amino acids.
- Different endpoints: height velocity in children vs CT-measured visceral fat in adults.
- No comparison exists: 12 co-mentions on PubMed, all reviews or doping tests; 0 head-to-head registrations.
Limits of this page
The sermorelin molecular weight is the approximate figure for GHRH 1-29 amide and is not taken from a current label, because no current label exists. The Geref paediatric study was open-label with no control group, so its height-velocity gain is a before-and-after figure. The Federal Register determination records why FDA believes Geref was not withdrawn; it does not state the sponsor's commercial reason. PubMed and registry counts depend on query wording and were taken on one date.
Sources and dates
- openFDA drugs@FDA, queried 2026-09-30: NDA 019863 and NDA 020443 (Geref, EMD Serono, both discontinued with the Federal Register determination); BLA 022505 (Egrifta, Theratechnologies, original approval 2010-11-10, type 1 new molecular entity).
- EGRIFTA SV and EGRIFTA WR prescribing information, openFDA label records effective 2026-07-29: sections 1, 2, 11, 12.3 and 14.
- 21 CFR 600.3(h)(6), definition of protein — eCFR, read 2026-09-30.
- Biologics Price Competition and Innovation Act of 2009, section 7002(e)(4), as reproduced in the statutory note to 42 U.S.C. 262, read 2026-09-30.
- Thorner M, et al.; Geref International Study Group. Once daily subcutaneous growth hormone-releasing hormone therapy accelerates growth in growth hormone-deficient children during the first year of therapy. J Clin Endocrinol Metab 1996;81:1189–96 — PMID 8772599
- PubMed, searched 2026-09-30:
tesamorelin[tiab]→ 94;sermorelin[tiab] OR "GHRH(1-29)"[tiab]→ 198; both → 12, all read by title and publication type. - ClinicalTrials.gov API v2, searched 2026-09-30: intervention
tesamorelin→ 24;sermorelin→ 27. - World Anti-Doping Agency, 2026 Prohibited List, section S2.2.4, read 2026-09-30.