Following some sinus surgery it was recommended I use an aerosol saline spray, which proved extremely effective. Not only did it aid in the healing process but eventually completely cleared my sinusitis, notoriously difficult to shake.
My surgeon was specific in his instructions to always sterilize the nozzle to avoid reinfection, which makes a lot of sense. He recommended rubbing alcohol which is what I use.
In fact, I filled a little baby food jar with it and keep it next to the aerosol so I never forget. I use the same bottle whenever I use my oral thermometer for the same reason.
So I’m wondering, though it was never mentioned to me, should I be changing the rubbing alcohol from time to time? And if so, how often?
Rubbing alcohol (isopropyl alcohol, to give it it’s chemical name) is basically a disinfectant. Anything that could contaminate it wouldn’t survive in it. It does evaporate quite easily though, so you’ll probably have to get some more eventually if you don’t screw the lid on properly.
If you’re talking about a contaminant that isn’t alive - sure.
I suspect you could find some way to “poison” isopropanol with lead, or some heavy metal.
Living things don’t do too well in isopropanol, that’s why it’s a decent mild disinfectant. Hell, living things don’t do too well in even fairly dilute ethanol solutions (beer, for example). Even yeast will ferment the drink until a point where the ethanol is just too toxic to continue supporting life. That’s why historically people in areas with bad drinking water have drunk beer and wine instead of water - it’s safer. Microbes generally don’t do too well in any kind of alcohol.
Isopropanol sitting on your shelf isn’t going to get contaminated with a biological contaminant unless you dilute the stuff to crazy low levels, either through adding water or progressively adding biological matter to the point where there’s a very low concentration of alcohol and a high concentration of “other”.
Dying bacteria produce fever-producing molecules called endotoxins. While endotoxins are normally regarded as a danger only in injectibles, they have been associated with allergic skin reactions in infants, and I suspect other sensitive populations would also be at risk. If you’ve dipping your thermometer and other contaminated stuff into it, you really need to replace it
it is always a good idea to dispense liquids from bottles. pour out what you need into a small container and don’t return any unused portion. or take a clean cloth or paper towel and wet that at the neck of the bottle.
in this particular case of externally used rubbing alcohol i wouldn’t be worried about enough bacteria being able to contaminate the bottle.
for a medical thermometer you could just wipe with wetted paper towel or tissue.