I was going through some of my first aid supplies yesterday and noticed that the bottles of rubbing alcohol had expiration dates on them. I was wondering if this is a case of the FDA mandating some form of expiration date of if in fact alcohol really does lose its potency or effectiveness after a period of time. Any ideas?

Over time, alcohol will absorb water which will reduce it's effectiveness. When I need it for regular use, I would just put the new in my stocks and rotate the old out and use it first. Even if you pass the expiration date, I don't think it would really hurt anything as long as you didn't let it get too old.

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Isopropyl alcohol oxidizes to acetone and can slowly form ethers and epoxides. This occurs very slowly while the bottle is closed but it happens much faster (but still pretty slowly) once the bottle is opened. So yes, rubbing alcohol expires. Once it's reached the expiration date, throw it out.
Source(s):
I'm a biomedical engineer. Organic chemistry occupies about 99% of my day.

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