# why does alcohol sting?

**URL:** <https://boards.straightdope.com/t/why-does-alcohol-sting/139795>\
**Category:** Factual Questions\
**Created:** [December 1, 2002, 6:22pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795 "2002-12-01T18:22:50Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Pantone\_Swatchbook](https://avatars.discourse-cdn.com/v4/letter/p/cc9497/32.png) [@Pantone\_Swatchbook](https://boards.straightdope.com/u/Pantone_Swatchbook)\
**Post date:** [December 1, 2002, 6:22pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795/1 "2002-12-01T18:22:50Z")

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Why is it so painful to apply alcohol (or other topical treatments like merchurochrome) on open wounds, as opposed to an inactive solution like water?

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**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\
**Post date:** [December 1, 2002, 7:00pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795/2 "2002-12-01T19:00:47Z")

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Alcohol is a weak acid. One gets a chemical burn when it is applied on damaged skin.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [December 1, 2002, 8:35pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795/3 "2002-12-01T20:35:08Z")

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Weak acid ? Alcohol is more of a dehydrating agent and disruptor of membranes. Here’s abrief review: [Disinfectants](http://www.bmb.leeds.ac.uk/mbiology/ug/ugteach/icu8/kill/chemical.html)

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**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\
**Post date:** [December 1, 2002, 9:40pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795/4 "2002-12-01T21:40:58Z")

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> [@](#):
>
> \*Originally posted by Squink \*  
> \*\*Weak acid ? Alcohol is more of a dehydrating agent and disruptor of membranes. \*\*

Membrane disruption is what acids do.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [December 1, 2002, 10:51pm UTC](https://boards.straightdope.com/t/why-does-alcohol-sting/139795/5 "2002-12-01T22:51:46Z")

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> [@](#):
>
> \*Originally posted by Qadgop the Mercotan \*  
> \*\*Membrane disruption is what acids do. \*\*

That may be, but the pKa of ethanol is about the same as that of water (15.9 vs 15.7). Neither are commonly considered to be “acids”. Nor are any of the other common alcohols, except phenol, particularly acidic.