Should I write the date on the vial?

Yes. Writing the mixing date on the vial is the easiest way to track the roughly 28-day window and know when to stop using it. It takes the guesswork out of how old a mixed vial is.

The whole guide to mixing peptides, step by step, in the order problems come up

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of shelf life after reconstitution. How long a peptide lasts once it is mixed, and how to store it.