This would be a GREAT question to ask your doctor.......
Does anyone know if Fentanyl would degenerate if left in a syringe for 5-6 days? How rapidly would this occur?
Don't mess with it. Don't mess with it. Talk to a medical professional.
I realize I said "Don't mess with it." twice. It was for a reason.
I assume your interest is purely theoretical.
Here's what the National Institute of Health says: