Article by: Perry Romanowski

When you are meeting with a cosmetic raw material supplier, they often talk about how their ingredient will penetrate the skin.  Even cosmetic marketers use the phrase “skin penetration” when advertising skin and anti-aging products. Penetration seems to be an important characteristic of cosmetics but have you ever thought about why anyone would want a cosmetic ingredient to “penetrate”?

What is skin penetration?

The term penetration is used to describe a characteristic of cosmetic ingredients in which they migrate from the surface of skin into the lower layers of the skin cells. Our skin is made up of a number of cell layers and some ingredients can penetrate deep into those layers. If you want your product to go below the surface of skin you want something that penetrates.

Why skin penetration

While many people tout penetration as a benefit there are only certain times you want your formulation to penetrate the skin. This would include situations in which you want to improve the feel of the formula upon application and when you want to make water resistant claims.

However, these are not the reason that most marketers (and some cosmetic chemists) desire skin penetration. Many people want their products to penetrate the skin to improve the effectiveness of the “active ingredient”. You see, there are a number of cosmetic ingredients and products that claim to interact with skin cell metabolism, increasing collagen production, or stimulating some other enzyme that will magically remove wrinkles. But the truth is if these ingredients actually could do this, the products would then be considered drugs and would require much more stringent & expensive testing (at least in the United States).
In the US any product that affects skin metabolism is a drug

Penetration enhancers

Although most penetration claims are for non-cosmetic purposes, there are still legitimate reasons that you would want your formulation to penetrate the skin. And for these, it is useful to use penetration enhancer ingredients.

Typical skin penetration ingredients include emulsifiers and solvents. Emulsifiers are surfactants that have both a hydrophobic segment and a hydrophilic segment on the molecule. They allow for compatibility between polar and non-polar ingredients. In a solution, they form micelles which can surround and encapsulate “active” ingredients. When place on the skin, the emulsifiers will penetrate deeper into the skin and bring whatever is encased in the micelle with it. Emulsion penetration can be enhanced by reducing the particle size of the emulsion. So, microemulsions and nanoemulsions are excellent skin penetrating vehicles. Phosphatidylcholine is a good penetration ingredient.

Solvents like propylene glycol are also excellent penetration enhancers. They can help shuttle soluble ingredients through the lipid top layers of the skin into the lower layers.

Penetration enhancing caution

There are times when you do not want your cosmetic to penetrate. This would include products that are cleansers as they can lead to irritation and colors because you want to be able to remove them. Also, cosmetics are designed to make superficial improvements so you also don’t want your product to penetrate down as far as the dermis where the living skin cells are. Once an ingredient gets to the dermis it could interact with skin cells and affect skin metabolism. And while this is what some marketers want to claim about their products, this is not something that you want to actually have happen.


  1. PJ

    Hi Perry,

    What gives products like Eucerin lotion that great light texture? Is there a key ingreient?

    Also I just stumbled across this blog post but do you have any recommendations for companies who help formulate manufacture and distribute cosmetic lines for start ups?

  2. Brooklynn Baker

    Why are pregnant women warned to stay away from certain ingredients, such as lactic acid and retinol… if it doesn’t penetrate to the blood stream?

    1. Perry Romanowski

      I don’t know. Perhaps a doctor could tell you

  3. Lindsay

    Hi! I like your article, although it did dissapoint me when I think about all the money I spent on skin care products. My question is..I read in another article that hyaluronic acid can actually penetrate skin because it has small enough molecules, therefore effective as far as aesthetic reasons. Is this true? If so, what are other examples that are small enough to penetrate skin?

    1. Perry Romanowski

      There is some evidence that HA can penetrate skin but it is not because the molecule is small. It may have more to do with its non-polar structure. I’m a bit skeptical that it can penetrate though.

  4. Jodie Dodd

    I found your article and comments very interesting. It has brought up a few questions.

    Could you please explain then, the difference between serums and moisturizers? My understanding is that the molecular size allows a serum to penetrate to the living layer of skin and that the moisturizer really only serves to protect and uphold your protective barrier layer buy locking in moisture.

    I come across many people that believe nowadays that simply by putting coconut oil, olive oil, avocado oil, or argan oil is enough to combat age and provide the function of both moisturizer, protectant, and or serum. Your thoughts?

    From an Oncology aesthetician standpoint to you believe then that products with glycol are completely safe to use as they would never penetrate to a layer of skin that could actually cause damage?

    Also, in your opinion is there any 100% natural product that is effective in treating oily acneic skin? My belief is that there is not, as acne skin needs a water based product line, and I have yet to find any that have a all natural stabilizer. I am of the opinion that all natural is not realistic unless you are making it up at home and using it up right away. What are your thoughts?

    1. Perry Romanowski

      The terms “serum” and “moisturizer” are simply marketing terms that don’t really have any scientific meaning. Molecular size has nothing to do with the terms. In the cosmetic industry “serum” just means a clear, slightly thickened liquid. A “moisturizer” is typically an opaque cream. Functionally, their differences depend on the ingredients in the formula. There are serums that moisturize and moisturizers that penetrate deeper into the skin.

      The oils you mentioned provide an emollient effect but they aren’t having any significant anti-aging effect.

      Yes, products with glycol are safe. There is no evidence they substantially damage skin.

      No, there in no effective 100% natural product that clears up acneic skin.

  5. Steven areia

    Is dimethicone bad for the skin

    1. Perry Romanowski


  6. Travis

    Thanks for the article Perry.

    I would think that a dermal delivery topical that actually delivered into the blood stream and CNS would only be considered a drug if the active ingredient is a drug, not a supplement. Can you please point me to any legal literature supporting the claim?

    Thanks in advance!

    1. Perry Romanowski

      If an ingredient penetrates the skin, gets in the bloodstream and has an impact on body metabolism it is by FDA definition a drug. Check the FDA website.

  7. Mai

    Hi, I found your article very interesting!
    I am currently working on making my own cosmetics with natural preservatives like vitamin E.
    I would like to ask you if you know if it is possible to make a cream myself with Phosphatidylcholine. I can order capsules from ebay, but I am not sure those are what I should add to my creams. Can you please advise on this? Also, if i would like to preserve the creams do you have a good suggestion or is vitamin E ok?

    I hope you find time to answer my questions.

    Best regards

    1. Perry Romanowski

      No phosphatidylcholine is not an adequate enough emulsifier to make a cream. No vitamin E is not an adequate preservative for cosmetics.

      1. Lucy

        Then what is an adequate, natural preservative? Ferments such as radish root? Leucidal Liquid SF? If neither of those meet your standards either, please share what you recommend.

        1. Perry Romanowski

          That really depends on what is in your formula and what you consider natural. Radish root is not an adequate preservative for most anything. Leucidial is a decent secondary preservative but will not work because it is not broad spectrum enough. Check our forum for natural preservative suggestions. Typically, an organic acid or phenoxyethanol but it depends on your system.

  8. Kang-Duck


    We, Science & Technology Laboratory Co., Ltd are a importer and distributor of skin measuring machine. And, we are very interested in measuring of the absorption and penetration rate of the skin with cosmetic.

    While we have been searching newly invented measuring machine for this task, the absorption and penetration rate, we read your artle. So, we think you know what machine is suitable for the measurement of this task or you have used for your project.

    If you have any information for the measuring machine of absorption and penetration rate of the skin, please introduce to us for Korean cosmetic and raw material manufacturers.

    Thank you and Sincerely,

    1. Perry Romanowski

      I’m not sure I understand your question. But you can contact me directly using the ‘contact us’ button at the top.

  9. Nina

    I have a question regarding makeup penetrating of the skin. I searched the internet for a long time for “save cosmetics” during pregnancy but I have found none. So I bought my own mineral makeup components and made it my self (Titanium dioxide non nano, zinc oxide non nano and iron oxides brown, yellow and red). I mix the mineral makeup with almond oil to apply to the skin. Before the makeup I apply beeswax with coconut oil to protect my skin.
    Do you think that the makeup can penetrate my skin and do harm during pregnancy? I am worrying sick about this, since I want to avoid that it would do harm to the baby during my pregnancy… Thank you for your help…

    1. Perry Romanowski

      Hopefully this will calm your concerns. You do not have to worry about makeup penetrating skin and causing any harm. Makeup (standard products you can buy in the store and your own) is perfectly safe and not something you need to worry about.

  10. Ceyda

    Hi Perry,

    I would like to learn why you ended this article with this sentence:

    “Once an ingredient gets to the dermis it could interact with skin cells and affect skin metabolism. And while this is what some marketers want to claim about their products, this is not something that you want to actually have happen.”

    Why we may not want them to interact with our skin cells in dermis? Is it dangerous? I thought it is a good thing because once they interact with the skin cells in dermis they can stimulate the collagen production which is a good thing, right?



    1. Perry Romanowski

      If a product interacts with the cells in the dermis it is no longer a cosmetic, it is a drug. And drugs face different regulations than cosmetics. Yes, it could be dangerous.

  11. True Skin: Skin Treatments

    However, a cleanser should remove dead cells and a moisturizer should increase water content, protect skin, and smoothness. I’m wondering what you suggest as a good natural emulsifier.

    1. Perry Romanowski

      Useful emulsifiers do not occur in nature and any one that is used in cosmetics would have to be produced in a laboratory. Whether you consider it natural if it is derived from coconut oil is really a matter of opinion. There is no legal definition for “natural”.

  12. Eli

    Do physical UV blocking agents like zinc and titanium need to penetrate the skin to be effective? Thanks

    1. Perry Romanowski

      Most likely not. Even nanoparticles of these ingredients haven’t been found to penetrate.

  13. Ateh

    Hello Perry,
    I was wondering if I am making a homemade self tanner using DHA, should I use a penetration such as Phosphatidylcholine because I actually want it to darken the dead skin cells.

    Thank you!

    1. Perry

      DHA will penetrate the outer layers of the skin rather well so an additional penetration enhancer is not typically necessary. But it really depends on what is in the rest of the formula.

  14. Pingback:Advances in penetration of skin creams

  15. Eliza

    Thank you, Perry, for addressing this issue! 🙂
    Do you have any suggestion for cosmetic ingredients that form a good barrier against penetration of irritants (oclussives)?
    Another question: say one formula combines penetration enhancers like surfactants and PG with irritants like certain fragrance materials (most essential oils contain many irritants), should a cosmetic chemist rather try to avoid happening? (for example a shampoo or soap including essential oils)

    Many thanks!

    1. Perry

      Silicones like Dimethicone are pretty good barriers.

      I don’t think you would generally have to avoid PG with fragrances unless you have a problem with a specific formula.

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