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06 2 / 2011

Anonymous said: Does rubbing alcohol ever go bad? The bottle in my medicine cabinet has an expiration date but I'm doubtful it will really expire. Please advise!

dear alysia (thanks for letting me know you submitted this question!),

rubbing alcohol typically found in stores is 70% isopropyl alcohol in water.  isopropyl alcohol is a very volatile liquid; this means that it evaporates very easily.  so, once you open (and subsequently keep opening) a bottle of rubbing alcohol, the solution’s potency will decrease over time due to the isopropyl alcohol slowly evaporating away as it is exposed to air. thus, it eventually does “expire” because after some time the ratio of alcohol to water may be significantly less than 70%, thus reducing its effectiveness.  note that if you leave the bottle open for long periods of time the solution may expire before the printed expiration date.

have additional questions on rubbing alcohol or expiration dates of other products?  let me know!

hope this helps.

hel

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