Tesamorelin vs sermorelin
Same receptor, different molecule, very different evidence.
Checked 2026-10-22 Researched and written by Kymata Health Editorial · Sources cited inline Report an error
Short answer
Both are GHRH analogs that make the pituitary release more of its own GH through the same receptor. Tesamorelin is the full 44-amino-acid GHRH with a stabilising group, has phase 3 trials and current US labels; sermorelin is the 29-amino-acid active fragment, with smaller, older studies. They have never been compared head to head.
How do the molecules differ?
Natural GHRH has 44 amino acids and is cut to an inactive form within minutes; its half-life after IV injection is about 7 minutes (Frohman 1986, J Clin Invest). Sermorelin is GHRH(1-29), the shortest fully active piece, with a half-life of 6 to 7 minutes after IV injection by its EU product information (Geref 50 SPC (HPRA)). Tesamorelin is the whole 44-amino-acid chain with a trans-3-hexenoyl group that slows that cleavage; its labels give 8 to 38 minutes depending on formulation and study (Egrifta WR label; Egrifta label, 2010).
How does the evidence compare?
Tesamorelin: two phase 3 trials in 816 adults with HIV (Falutz 2007, NEJM; Falutz 2010, JAIDS), liver-fat trials (Stanley 2019, Lancet HIV) and a cognition trial (Baker 2012, Arch Neurol). Sermorelin: smaller studies, such as twice-daily GHRH(1-29) restoring 24-hour GH and IGF-1 in older men (Corpas 1992, JCEM) and nightly doses that raised night-time GH but not IGF-1 (Vittone 1997, Metabolism).
Can they be taken together?
They press the same receptor, whose response tops out near 1 µg/kg (Gelato 1984, JCEM), so a second GHRH analog is expected to add little. No study has given the two together.
Frequently asked questions
Questions
- Is sermorelin still sold as Geref?
- No. Its US approvals were withdrawn in 2009 at the maker's request, not for safety or effectiveness reasons.
Not medical advice This page summarises published labels and studies. It is not a recommendation to use any product; a clinician decides.