# Can caffeine be absorbed by the skin? **URL:** \ **Category:** Factual Questions\ **Created:** [September 29, 2014, 3:54pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871 "2014-09-29T15:54:53Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [September 29, 2014, 3:54pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/1 "2014-09-29T15:54:53Z")
Ok, another great sales pitch - caffeinated shaving cream. Yes. You, too, can get up from a short night’s sleep, simply shave with this product, and be alert all day long. > **[Pacific Shaving Company | Innovative. Effective. Shaving Care for Men.](https://www.pacificshaving.com/)** > > Pacific Shaving Company | Pacific Shaving Company | Innovative. Effective. Shaving Care for Men. Safe, natural, and plant-derived ingredients. Family-run, since 2002. Not bloody likely, I’m thinking. So, in the amount of time that shaving cream stays on a person’s skin, how little - if any - would be absorbed and make it to the blood stream? How much is that, compared to the amount in, say, a cup of coffee? ---
**Author:** ![halfreal](https://avatars.discourse-cdn.com/v4/letter/h/ccd318/32.png) [@halfreal](https://boards.straightdope.com/u/halfreal)\ **Post date:** [September 29, 2014, 4:20pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/2 "2014-09-29T16:20:04Z")
That website doesn’t seem to claim that their cream can replace coffee in terms of effects; rather on the contrary, the “learn more” link takes you to [Put caffeine on your mug, not in it. Caffeinated Shaving Cream and Aftershave Set](http://www.pacificshaving.com/products/NEW!-Caffeinated-Shaving-Cream-%26-Aftershave-Moisturizer-Set.html) , which explains that the intended effect is primarily a direct one on the skin. The concept of caffeine being absorped by the skin (and even more so, through hair follicles) and having positive effects seems to be legit: [Caffeine and Skin Care Products](http://www.caffeineinformer.com/caffeine-and-skin-care-products) ---
**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:** [September 29, 2014, 4:51pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/3 "2014-09-29T16:51:19Z")
Yes, caffeine is absorbed topically. [The role of hair follicles in the percutaneous absorption of caffeine](http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2125.2007.03065.x/full) discusses the phenomenon. > [@](#): > > Caffeine, a naturally occurring purine based alkaloid, is frequently used as a hydrophilic model substance in skin penetration experiments. Caffeine penetration was shown to be unchanged by occlusion and skin thickness ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [September 29, 2014, 4:52pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/4 "2014-09-29T16:52:59Z")
Is there a time frame, QtheM? In other words, does topical caffeine sink in right away, or is it a matter of the longer it sits on the skin the more you absorb? ---
**Author:** ![halfreal](https://avatars.discourse-cdn.com/v4/letter/h/ccd318/32.png) [@halfreal](https://boards.straightdope.com/u/halfreal)\ **Post date:** [September 29, 2014, 5:19pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/5 "2014-09-29T17:19:03Z")
I’m not QtheM, but if you don’t mind: > [@](#): > > [Results > Caffeine (3.75 ng ml−1) was detected in blood samples, 5 min after topical application, when the follicles remained open. When the follicles were blocked, caffeine was detectable after 20 min (2.45 ng ml−1). Highest values (11.75 ng caffeine ml−1) were found 1 h after application when the follicles were open.](http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2125.2007.03065.x/abstract) ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [September 29, 2014, 5:26pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/6 "2014-09-29T17:26:04Z")
Caffeine is fairly soluble in [DMSO](http://en.wikipedia.org/wiki/Dimethyl_sulfoxide), which I suppose could facilitate absorption. Not that it’s a good idea. ---
**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:** [September 29, 2014, 5:48pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/7 "2014-09-29T17:48:36Z")
What **halfreal** said. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [September 29, 2014, 6:35pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/8 "2014-09-29T18:35:41Z")
FWIW, Pacific Shaving’s regular shave cream is terrific stuff, so it’s likely the caffeinated kind is pretty good as well. ---
**Author:** ![rn4j0r](https://avatars.discourse-cdn.com/v4/letter/r/8e7dd6/32.png) [@rn4j0r](https://boards.straightdope.com/u/rn4j0r)\ **Post date:** [September 29, 2014, 6:39pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/9 "2014-09-29T18:39:10Z")
Just like how tobacco can be absorbed in your mouth, the same can happen with caffine. ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [September 29, 2014, 8:14pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/10 "2014-09-29T20:14:01Z")
Ok - it looks as if there are some tiny amounts of caffeine that can be absorbed during shaving. The ads for the shaving cream, however, seem to imply, indicate, hint and move the less-discerning reader to think that the shaving cream will do the same thing that coffee does. Yes, they say, " It may not replace your morning coffee, but it will give a little extra kick to your morning routine." but that seems to be misleading just a tad. But, ok, I have my answer. Thank you, Dopers. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [September 29, 2014, 10:05pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/11 "2014-09-29T22:05:24Z")
> [@rn4j0r](#): > > Just like how tobacco can be absorbed in your mouth, the same can happen with caffine. Yeah, but absorption through mucus membranes isn’t the same as absorption through, say, the skin on your arm. ETA: thanks, **halfreal**! ---
**Author:** ![teela\_brown](https://avatars.discourse-cdn.com/v4/letter/t/d9b06d/32.png) [@teela\_brown](https://boards.straightdope.com/u/teela_brown)\ **Post date:** [September 29, 2014, 11:21pm UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/12 "2014-09-29T23:21:48Z")
I’ve always wondered about baristas, and how they handle and touch coffee grounds all day long. Not to mention standing in and probably inhaling a cloud of atomized grounds as well. They probably need to drink no coffee at all! ---
**Author:** ![D18](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@D18](https://boards.straightdope.com/u/D18)\ **Post date:** [September 30, 2014, 1:52am UTC](https://boards.straightdope.com/t/can-caffeine-be-absorbed-by-the-skin/699871/13 "2014-09-30T01:52:22Z")
I tried to find comparative blood caffeine levels after drinking a cup, but came up empty. Anyone know?