What is the Botox Shelf Life?

I wanted to clarify that Botox cosmetic comes in either 50 or 100 units.
If kept cold, each vial has an expiration date printed on the vial.
Once prepared the manufacturer's instructions state that the Botox is good for 4 hours.
However, in clinical practice , many studies have shown that the Botox is active for at least two weeks if kept cold.
In most busy practices it would be unusual that a vial would not be used the day it was opened and certainly withon the next office day.
I hope this helps.

Botox does not have a 500 unit vial that we know of. We have always purchased 100 unit vials.
Botox has an expiration date on it if is has not been mixed with saline. If it has been mixed with saline, we have used it up to several weeks after mixing and it still works fine. We are not sure exactly how long after mixing it would take before losing effectiveness.

Allergan Botox comes in a vial of 100 units. I am not familiar with the one you are quoting. Once it is diluted, most physicians feel that it keeps well for two weeks or even more in the refrigerator (it is frozen while stored prior to mixing). Most physicians who perform excellent Botox injections never have that concern as the bottle doesn’t last more than a few days in their practice. The volume of patients undergoing the treatment means that the office needs to open a new vial very frequently.