Prescribed vials are safe for more than a month, and the preservatives in them last longer than a month (this is also true for DIY vials, which are often used for as long as a year or more). They can be compromised any time, though - so it makes sense still to refill your Rx once a month. (My endo originally didn’t have me refill my vials once a month and expected me to use my vials for many months, he had no concerns about the safety, but was willing to write the Rx to refill once a month based on my argument that the FDA recommends pitching vials after a month. This was especially a concern I had after I cored some vials and was going to run out of medication.)

I use prescribed vials (100 mg estradiol valerate in 5 mL) for 3+ months without issue, they are more likely to core and be compromised that way than to become unsafe from pathogens from drawing (because of the preservatives). This makes it more important that you use thin needles for drawing, and use proper technique to avoid coring. Of course this is also why it’s so important to wash your hands before starting the injection, why you sanitize the vial with an alcohol swab, and why you don’t re-use needles, etc. Sterile needles going into a sterilized rubber stopper won’t be a big risk, and the air that has pathogens will be made safe by the preservatives.

The current vial I’m using in October was opened in February (8 months so far).

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)

most preservatives in vials can last roughly 4-5 years in optimal conditions (away from sunlight and kept cool) though this will most likely be impacted by using the vial, youd run out of medication before the preservatives went rancid

I am not a medical professional and my advice is of one who has no credentials or qualifications for this.

I’ve helped an undisclosed individual with cleaning vials.

This assumes that the vial fluid has not broken down, this instruction is to remove pathogens, not rancid fluid other toxins floating in the vial.

You need a glass filter like this, with the smallest pore size. https://www.hawachfilters.com/glass-fiber-syringe-filters.html

The reason for this is that most bacterium are over half a micron long. You’re unlikely to find anything smaller surviving in the fluids of your medication vial, viruses being even more rare inside.

Afterwards, you’ll need a new sterile bottle to fill.

Ensure your environment is sterile, or as clean as possible without airflow. ensure all equipment is clean and sterilized too.

1. Use an 18g needle on a syringe of sufficent sizr to draw out of the vial contents that either is 1 month old, or has rubber filaments in it from a damaged cap.
2. Once your syringe is filled with the vial contents, remove the 18g needle & install the filter.
3. Install a 25g needle to the M port of the filter. The reason for this is to ensure the smallest hole possible in the new vials seal.
4. Insert into the new vial.
5. At this point, you will want to take a spare 25g needle (no syringe) and insert it into the vial on the opposite side of your filling syringe. This is for pressure difference.
6. In a blood curdilingly slow speed, slowly push all the medication through the filter into the vial. Take it as slow as possible, this is not a fast process, it will take 10+ minutes.
7. Once as much of the medication is through as possible, you have a generally filtered and clean vial of your medication.

The undisclosed individual was able to use the vial to completion without infection or issue, then resumed using clean vials.