How Long Does Tesamorelin Last? Before and After Mixing
Lyophilised tesamorelin is stable for years when kept sealed, dry and cold, but once mixed with bacteriostatic water it lasts about a week at most, the shortest window of any peptide Vistara Labs supplies. The approved prescription formulation is labelled to be discarded 7 days after mixing, and Vistara Labs’ handling guidance applies the same clock to a research vial kept at 2 to 8 °C in the dark. A mixed vial is never frozen, and the powder is best mixed close to when it is needed.
Findings
- Tesamorelin is the full 44-amino-acid sequence of human growth hormone releasing factor with a hexenoyl group added to its first tyrosine (US prescribing information, 2025).
- A chemical supplier rates the solid at at least 4 years at −20 °C (Cayman Chemical, tesamorelin acetate).
- The approved 11.6 mg formulation is discarded 7 days after mixing; its bacteriostatic water bottle gets 28 days from first use.
- Its sequence includes asparagine at positions 8 and 35 and a methionine at 27, the residues that limit how long growth hormone releasing factor peptides last in water.
How long does tesamorelin powder last?
Dry, tesamorelin is robust. Cayman Chemical supplies the acetate salt as a solid stored at −20 °C with a stated stability of at least 4 years. The approved 11.6 mg vials are a different case worth knowing about: they are kept at controlled room temperature, 20 to 25 °C, in the original box to protect them from light, with brief excursions to 15 to 30 °C permitted. That powder also contains a cyclodextrin and mannitol as inactive ingredients, so its room-temperature rating belongs to that product. For a plain research vial, the fridge or freezer in the box is the conservative choice, with the vial warmed to room temperature before opening so that no condensation reaches the cake.
How long does tesamorelin last after mixing?
About a week at most. The approved formulation’s label says one mixed vial provides 7 days of use and that any solution left after 7 days is discarded. Vistara Labs’ handling guidance applies that 7-day limit to research vials as well, with the vial kept at 2 to 8 °C, dark and upright. The method and the volume arithmetic are on the tesamorelin reconstitution page, which includes a calculator.
Why so much shorter than other peptides?
Most peptides on the store’s list hold up for 8 to 12 weeks once mixed. Tesamorelin is longer than nearly all of them, and length means more vulnerable residues. Its asparagines at positions 8 and 35 can deamidate, and its methionine at 27 can oxidise. The asparagine at position 8 is the one that matters most: a 1991 study of growth hormone releasing factor analogues found that breakdown in neutral solution tracked deamidation at that site, and that swapping it for serine extended the analogues’ half-life in solution more than sevenfold, from 202 to 1,550 hours at 37 °C (Friedman et al., Int J Pept Protein Res). Tesamorelin keeps the native asparagine. Its hexenoyl group makes the start of the chain resistant to the enzyme dipeptidyl peptidase 4 (Cayman Chemical product information), which matters in plasma but does not stop these chemical reactions in the vial.
Mix close to use
Tesamorelin is the compound most often reported to gel or turn hazy, a problem covered in why peptides gel or go cloudy. Cayman’s product sheet advises against keeping its unpreserved buffered solution for more than a day. Together with the 7-day label limit, that is why the guidance is to mix one vial at a time and close to when it is needed.
How long does tesamorelin last at room temperature?
The approved 11.6 mg formulation is actually stored at room temperature after mixing: its label says to keep the mixed solution at 20 to 25 °C and not to refrigerate or freeze it. The 2 mg formulation, which is mixed with sterile water instead, is used straight away and never stored. Both instructions are tied to those manufactured formulations and their excipients. For research vials, Vistara Labs’ guidance is the fridge, and the 7-day limit applies whichever way the vial is kept.
Can tesamorelin be frozen?
The solid can be kept frozen; Cayman’s 4-year figure is at −20 °C. A mixed vial cannot. Both approved formulations say not to freeze the mixed solution, and freezing and thawing aggregates peptides in solution in any case.
How can you tell mixed tesamorelin has degraded?
The label describes a correctly mixed solution as clear and colourless, and says not to use it if solid particles appear or if it is cloudy or coloured. The signs to look for:
- Cloudiness that does not settle after 10 to 15 minutes.
- Gel, thickening or a stringy look when the vial is tilted.
- Particles or flakes.
- Any colour.
- More than 7 days since mixing, even if it still looks clear.
Travelling with tesamorelin
Because the mixed window is so short, tesamorelin travels best as sealed powder, mixed on arrival. If a mixed vial must travel, it goes cold in an insulated case, upright and padded, with the mixing date on the label; the peptide travel case holds vials and cold packs. There is no tesamorelin nasal spray. It is also part of the Tesamorelin + Ipamorelin Stack, where each vial keeps its own clock once mixed.
Tesamorelin storage at a glance
| State | Where | How long |
|---|---|---|
| Research solid, sealed | −20 °C | At least 4 years (supplier rating) |
| Approved 11.6 mg vial, unmixed | 20 to 25 °C, in box | To the label date |
| Mixed research vial | 2 to 8 °C, dark | About a week at most (store guidance) |
| Approved 11.6 mg vial, mixed | 20 to 25 °C | 7 days, then discard |
| Mixed, frozen | Not recommended | Discard |
Certificates of analysis are on the lab reports page, and every order ships from within Canada by Canada Post Xpresspost.
Vistara Labs supplies tesamorelin as a laboratory research material. Label details for the approved medicine are quoted to explain the storage windows, not as instructions for any other use.
Frequently asked questions
How long does tesamorelin last in the fridge after mixing?
About a week at most. The approved formulation is discarded 7 days after mixing, and Vistara Labs’ handling guidance applies the same limit to a research vial kept at 2 to 8 °C.
Can tesamorelin be kept at room temperature?
The approved 11.6 mg formulation is stored at 20 to 25 °C before and after mixing, an instruction specific to that product. Research vials are kept in the fridge once mixed, and the 7-day limit still applies.
Can you freeze tesamorelin?
The dry solid can be stored at −20 °C, rated for at least 4 years by one supplier. A mixed solution should never be frozen.
Does tesamorelin go bad?
Yes, faster than most peptides once mixed, largely because of the deamidation-prone asparagine at position 8. Cloudiness, gel, particles or colour mean it has degraded.
How long does tesamorelin last in the body?
Briefly. The US prescribing information gives a mean elimination half-life of 11 minutes in healthy volunteers.
Handling windows: Vistara Labs, October 2026. Sources: US prescribing information for tesamorelin, 11.6 mg per vial formulation, sections 2.2, 11, 12.3 and 16, revised March 2025 (FDA reference ID 5557578). PDF. US prescribing information for tesamorelin, 2 mg per vial formulation, storage and handling. Label text. Cayman Chemical. Tesamorelin (acetate), item 42498, product information. PDF. Friedman AR et al. Degradation of growth hormone releasing factor analogs in neutral aqueous solution is related to deamidation of asparagine residues. Replacement of asparagine residues by serine stabilizes. Int J Pept Protein Res. 1991. PMID 1904406.
More on this: How Long Do Peptides Last After Mixing?
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
