Follow the label, not the internet
Storage requirements differ by product, formulation and whether something has been reconstituted. Your product label and pharmacy instructions are authoritative. General guidance — including everything below — is context, not instruction.
Temperature
Many peptide products require refrigeration, typically in the region of 2–8°C. Refrigerated does not mean frozen. Freezing can denature peptides and damage the formulation, and a product that has frozen should not be used even after thawing.
Store toward the middle or back of the fridge, not in the door. Door shelves swing through the widest temperature range every time the fridge opens, which is exactly what you are trying to avoid.
If a product is supplied at room temperature, keep it somewhere genuinely stable — not a bathroom cabinet, not a car, not a windowsill.
Light and air
Keep products in their original carton until use. The packaging is doing a job: shielding from light, protecting the stopper from contamination, and keeping the label with the product.
Never decant medication into another container. You lose the label, the expiry date, the lot number and the protection, all at once.
Travel
Plan cold-chain transport in advance. An insulated pouch with a gel pack works for a day; longer trips need more thought. Keep medication in carry-on rather than checked baggage — hold temperatures are not controlled and lost baggage is a real risk.
Carry your prescription documentation. Airport security handles medication and syringes routinely when they are labelled and documented.
When to stop and ask
Do not use a product that has frozen, been left out well beyond its stated window, changed colour, become cloudy, developed particles, or arrived with damaged packaging or a compromised seal.
Contact the pharmacy instead. Products damaged in transit are a known situation with a known process, and using a questionable vial to avoid a phone call is a poor trade.