There's a lot of confusion about peptide storage. Here's what the literature supports:
Lyophilized (freeze-dried) peptides:
- Short term (weeks): room temperature is fine
- Medium term (months): refrigerator (2-8°C)
- Long term (years): freezer (-20°C)
- Avoid repeated freeze-thaw cycles
Reconstituted peptides:
- Refrigerator (2-8°C) for 2-4 weeks max
- Use bacteriostatic water (not sterile water) to prevent bacterial growth
- Protect from light
- Do NOT freeze reconstituted peptides — it degrades them
GLP-1 specific:
- Semaglutide and tirzepatide are relatively stable
- Retatrutide is less stable — use within 2 weeks of reconstitution
This is based on published stability data, not vendor marketing.