# Caffeinated soap? Does this stuff work? **URL:** \ **Category:** Factual Questions\ **Created:** [June 23, 2003, 6:38pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835 "2003-06-23T18:38:38Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Lucki\_Chaarms](https://avatars.discourse-cdn.com/v4/letter/l/9de0a6/32.png) [@Lucki\_Chaarms](https://boards.straightdope.com/u/Lucki_Chaarms)\ **Post date:** [June 23, 2003, 6:38pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/1 "2003-06-23T18:38:38Z")
I almost put this in MPSIMS, because the main reason I’m posting it is just that I think it’s cool/funny, but I’m also interested in the science behind this concept. Does this work, or is it more just for the shock value and novelty appeal? [Check it out](http://www.xoxide.com/noname16.html) and let me know what you think. It seems pretty cool to me, if it works. Bonus points for that being an overclocking/computer modification page, with a whole section for caffeine products. I’m imagining that guy from _The Score_, who was constantly playing Unreal, or whatever it was. Anyways, if anyone knows about the actual logistics of this stuff, please do share. LC ---
**Author:** ![DiLLiGaF](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@DiLLiGaF](https://boards.straightdope.com/u/DiLLiGaF)\ **Post date:** [June 23, 2003, 6:59pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/2 "2003-06-23T18:59:47Z")
My question is why would you want to eat soap in the first place?? Just kidding. I remember reading a thread last week about water absorption in the shower. The consensus was that there is very little absorption due to your skin being waterproof. Sorry I can’t provide and solid facts as to the caffinated soap, but my thoughts are that it is a novelty that doesn’t really do anything. ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [June 23, 2003, 7:13pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/3 "2003-06-23T19:13:59Z")
[Thinkgeek.com](http://Thinkgeek.com) sells this stuff and claims the caffeine is absorbed through the skin. I have no idea if that’s true. I’ve had several friends who worked in cafes claim they got a huge buzz just working there, not drinking any beverages. I suspect this was from breathing in a lot of coffee bean dust from the grinder since they weren’t handling beans or other products with their bare hands. Maybe the caffeine in the soap gets inhaled along with that nice peppermint scent. ---
**Author:** ![UrbanChic](https://avatars.discourse-cdn.com/v4/letter/u/9dc877/32.png) [@UrbanChic](https://boards.straightdope.com/u/UrbanChic)\ **Post date:** [June 23, 2003, 7:20pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/4 "2003-06-23T19:20:04Z")
[Here’s a link](http://www.erowid.org/ask/ask.cgi?ID=3010) to the very same question posted over at Ask Erowid. > [@](#): > > A search for scientific studies about the permeability of caffeine through mammalian skin yielded several webpages describing caffeine’s poor ability to be absorbed transdermally. While one page did describe caffeine as having “good penetrating capability”, this was in a study in which the skin was exposed for 4 hrs using radioactivly labelled caffeine. Even then, with a 1 mg or 9.3 mg caffeine per 100 cm^2 area of skin the absorbed dose was calculated to be only 17% and 1.6%. > [@](#): > > Caffeine’s octanol:water partitioning constant is quite low, indicating it is very water soluble and very fat insoluble. This is sufficient for oral consumption of caffeine, because to get into the bloodstream it only has one or two cell layers to get through. However with skin, you have a thick layer of dead cells before you even get to the lower, blood vessel-containing dermis. It is possible, although unlikely, that the presence of soap could increase the membrane/cell permeability of caffeine, but it seems far more likely that the soap and water will keep the caffeine from being in contact with the skin. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [June 23, 2003, 9:25pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/5 "2003-06-23T21:25:54Z")
The page says “out of stock,” so either it’s a joke or lots of folks have been ordering it. If the latter, I’d say the soap works just fine, if you define “works” as “sells really well to people who don’t know better.” ---
**Author:** ![Freiheit](https://avatars.discourse-cdn.com/v4/letter/f/e8c25b/32.png) [@Freiheit](https://boards.straightdope.com/u/Freiheit)\ **Post date:** [June 23, 2003, 9:39pm UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/6 "2003-06-23T21:39:50Z")
I’ve seen it in stock before. ---
**Author:** ![Lucki\_Chaarms](https://avatars.discourse-cdn.com/v4/letter/l/9de0a6/32.png) [@Lucki\_Chaarms](https://boards.straightdope.com/u/Lucki_Chaarms)\ **Post date:** [June 24, 2003, 3:58am UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/7 "2003-06-24T03:58:01Z")
So, is the consensus that the item is interesting as a novelty, but isn’t likely to be very effective? Is there anyone who feels that they can make an authoritative statement about caffeine’s dermal penetration abilities? They say that it’s “caffeine anhydrous”. That sounds familiar from chemistry class, but I can’t remember what it means. Would that make it more likely to be absorbed? LC ---
**Author:** ![stringy](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@stringy](https://boards.straightdope.com/u/stringy)\ **Post date:** [June 24, 2003, 10:29am UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/8 "2003-06-24T10:29:29Z")
I don’t know about caffeine’s dermal penetration capabilities, but I’ve made my own coffee soap before, using melt-n-pour glycerine and fine coffee. Although it strongly smells of coffee, which is nice for a shower first thing in the morning, noone who used it (sample size: 5) reported getting any noticeable caffeine hit. It’s fun, and a good laugh for coffee addicts, but if you really need the caffiene I’d suggest a nice, hot espresso… ---
**Author:** ![neutron\_star](https://avatars.discourse-cdn.com/v4/letter/n/51bf81/32.png) [@neutron\_star](https://boards.straightdope.com/u/neutron_star)\ **Post date:** [June 24, 2003, 10:46am UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/9 "2003-06-24T10:46:37Z")
> [@](#): > > \*Originally posted by Cervaise \* > \*\*The page says “out of stock,” so either it’s a joke or lots of folks have been ordering it. If the latter, I’d say the soap works just fine, if you define “works” as “sells really well to people who don’t know better.” \*\* It’s in stock at [ThinkGeek](http://www.thinkgeek.com/caffeine/accessories/5a65/), although, based on that Erowid article, I’m not going to be purchasing it any time soon. ---
**Author:** ![papergirl](https://avatars.discourse-cdn.com/v4/letter/p/aca169/32.png) [@papergirl](https://boards.straightdope.com/u/papergirl)\ **Post date:** [June 24, 2003, 11:45am UTC](https://boards.straightdope.com/t/caffeinated-soap-does-this-stuff-work/183835/10 "2003-06-24T11:45:15Z")
As a soapmaker, I’m doubtful. Lye is such a strong caustic (as is the soap itself when it’s at the stage where you would add anything to it) that I can’t see much surviving it intact. I’d want some documentation about the actual content of caffeine in the _finished_ product, as well as more info about the possible absorption factors. If you’re that hard up for caffeine, you’d be better off to make up a nice coffee scrub out of some ground coffee and almond oil…mmm, that sounds kinda nice, actually. Off to the laboratory! Best, karol