# Why does my bag of Epsom salts say "Sodium Soak"?

**URL:** <https://boards.straightdope.com/t/why-does-my-bag-of-epsom-salts-say-sodium-soak/665600>\
**Category:** Factual Questions\
**Created:** [August 7, 2013, 4:46pm UTC](https://boards.straightdope.com/t/why-does-my-bag-of-epsom-salts-say-sodium-soak/665600 "2013-08-07T16:46:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\
**Post date:** [August 7, 2013, 4:46pm UTC](https://boards.straightdope.com/t/why-does-my-bag-of-epsom-salts-say-sodium-soak/665600/1 "2013-08-07T16:46:18Z")

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I have 4 lb bag of Up & Up (Target) brand Epsom salts. The front reads (preserving the formatting as best I can):

> [@](#):
>
> epsom salt  
> magnesium sulfate  
> USP (heptahydrate)
> 
> saline laxative for relief of  
> occasional constipation  
> soaking aid for minor  
> sprains and bruises  
> _ **Sodium soak** _

[Emphasis in the original]

The ingredients are 100% magnesium sulfate.

Is the “sodium soak” part a mistake? Does it have some other meaning I’m not aware of? There’s no sodium I could find here, so unless it means something like “soaks up sodium,” I don’t understand why it has that on the label. It’s just been bugging me for the past few weeks.

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**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\
**Post date:** [August 7, 2013, 4:51pm UTC](https://boards.straightdope.com/t/why-does-my-bag-of-epsom-salts-say-sodium-soak/665600/2 "2013-08-07T16:51:11Z")

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My guess is that it is intended to be used the same way a sodium-chloride soak would be used. Sort of like how people sometimes still say “tin foil” when the foil is actually aluminum.