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Caffeine Soap; does it really work?

  1. Sep 12, 2012 #1
    Evening all,

    I've been curious about these caffeine soaps lately and thought that this would be the place to discuss about it.

    My almost-favorite website United Nuclear claims:

    "As it turns out, our good old friend Caffeine
    reaches the bloodstream faster through skin absorption
    than ingesting caffeinated beverages such as coffee or energy drinks."

    Soap: http://unitednuclear.com/index.php? main_page=product_info&cPath=29_54&products_id=447

    So I browsed for chemical exposure websites and got this CDC site: http://www.cdc.gov/niosh/topics/skin/

    "Dermal Absorption

    Dermal absorption is the transport of a chemical from the
    outer surface of the skin both into the skin and into the body.
    Studies show that absorption of chemicals through the skin can
    occur without being noticed by the worker, and in some cases,
    may represent the most significant exposure pathway. Many
    commonly used chemicals in the workplace could potentially
    result in systemic toxicity if they penetrate through the skin
    (i.e. pesticides, organic solvents). These chemicals enter the
    blood stream and cause health problems away from the site of entry.

    The rate of dermal absorption depends largely on the outer layer of the
    skin called the stratum corneum (SC). The SC serves an important barrier
    function by keeping molecules from passing into and out of the skin, thus
    protecting the lower layers of skin. The extent of absorption is dependent
    the following factors:

    Skin integrity (damaged vs. intact)

    Location of exposure (thickness and water content of stratum corneum; skin temperature)

    Physical and chemical properties of the hazardous substance

    Concentration of a chemical on the skin surface

    Duration of exposure

    The surface area of skin exposed to a hazardous substance"

    The last three are immediately relevant (though others are quite significant).
    1. "Concentration of a chemical on the skin surface"
    Shower water and initial soap concentrations are limiting factors.

    2. "Duration of exposure"
    Leaving it on for 1 minute versus 15 minutes would make quite a difference.

    3. "The surface area of skin exposed to a hazardous substance"
    Well, caffeine isn't exactly monomethylhydrazine, but an increased applied area of soap definitely would increase the total amount absorbed.

    All three are no-brainer statements of course but definitely a decent place to start.
    Think-Geek has a similar soap that are 4 ounce bars with
    200 milligrams of Caffeine each. Comparing it to caffiene data (mg) from coffeefaq.com:

    7oz coffee:
    Drip 115-175mg
    Brewed 80-135mg
    Instant 65-100mg

    It seems like coffee has no chance versus caffeine soaps,
    but nevertheless I believe the actual amount of caffeine from the soap
    absorbed by the body is substantially lower. (That's my personal hunch, anyways.)

    It should be interesting to see what others have to say.


  2. jcsd
  3. Sep 12, 2012 #2
    Ha, I actually bought my mother some caffeine soap as sort of a joke gift a few years back. I'll have to ask her if it worked!
  4. Sep 13, 2012 #3


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    Gold Member

    I wonder how long I would have to stand there all lathered up before I could; rinse off, dry off, get dressed, and go make a pot of coffee.:smile:
  5. Sep 14, 2012 #4


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    Staff Emeritus
    Science Advisor

    Even if caffeine does get absorbed into the body through the skin, I doubt you use all 4 ounces of the bar of soap each time you bathe. I know it takes me a while to get through 1 bar of soap, not 1 or 2 times in the tub.
  6. Sep 19, 2012 #5


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    Homework Helper
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    But if one eats the remaining soap -- as a snack -- before one leaves the tub, that might do the trick.
  7. Sep 25, 2012 #6
    I asked my mom and she said she couldn't feel much effect if any.
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