I’m talking about prescribed vials which are meant to only be used for a month and not the diy vials which have enough for a whole year. I know that the preservative they use can’t really go beyond a month. And that if the preservative fails you might be injecting a pathogen directly into your body which is not optimal.
Same disclaimer as clocks about not being a medical professional, but I’m pretty sure they will last longer than a month. Typically they say this because that’s how long it has been tested for, and not because that’s how long it will actually last. I dunno if the preservatives used in prescribed vials are all that different from those used in DIY vials, but in the case of DIY they last around a year, probably longer.
Being cautious is ofc best. I would check the ingredients of DIY vials and compare to the ingredients in your vials or see if someone has talked about this elsewhere.
Another thing which is related and is more about stretching out the E you have is to take a smaller dose but more often. https://estrannai.se/ Despite injecting less E in total you can still have the same trough level (low)
tbh injecting more frequently also avoids / reduces mood swings and other symptoms from too much and too little E - great idea all around, pre-op I injected EV every 3.5 days (twice a week).