skin deep

Where Does All the Skin Care Go?

Photo: Pablo Croatto/Westend61/Getty Images

Perhaps you’ve come across this oft-cited statistic: 60 percent of skin care absorbs into your bloodstream. (If you ask Gwyneth Paltrow, that number shoots up to 70 percent.) Hard data says otherwise — there’s no way to quantify exactly how much skin care gets “soaked” up by your blood. There is not, in fact, a cocktail of vital fluids and vitamin C serum coursing through your veins as we speak.

But where does all the skin care go?

Once applied, does it sit on top of your skin? Does it “sink into your pores,” as the beauty bloggers say? And then what — does it pool at the bottom of the pore? Can it get past the bottom of the pore? If so, is there skin care floating in your lymphatic fluid at this very second? Does any actually make it to your blood?

I took my questions to the experts and the answer, to all of the above, is yes. Depending on the ingredient, skin care can go any number of places: Pores! Blood! Breast tissue! Mostly, though, it goes nowhere.

“The skin is the largest organ in the body. Its job is to protect you from external agents that might cause harm, and it does a very good job at that,” Ron Robinson, cosmetic chemist and founder of BeautyStat Cosmetics, tells the Cut. Skin has what Robinson calls an “armor” in place to defend against “potential aggressors” like bacteria and beauty products. That would be the skin barrier, or the stratum corneum.

The stratum corneum has lots of microscopic moving parts: the microbiome, the acid mantle, the lipid barrier, a layer of dead skin cells sometimes compared to a brick wall. They come together to form a waxy, water-repellent shield of fatty acids, sebum, and ceramides, which seals the skin’s natural moisture in and keeps external moisture out. This is a good thing; it’s why you can luxuriate in the occasional bath and still lead a long, non-waterlogged life. But it’s also a bummer, because skin care consists of a lot of water.

A quick scan of the ingredient labels in your bathroom cabinet can confirm: Water is typically the top-listed ingredient. Both the Dr. Barbara Sturm Hyaluronic Acid Serum ($300) and the Vichy Hyaluronic Acid Serum ($20) are mostly water, and around one percent hyaluronic acid. Reports estimate water-based products can be anywhere from 70 percent to 90 percent water, because water is an effective way to dissolve and dilute active ingredients and also the cheapest way to fill a bottle. An engineer for skin-care manufacturer Amway once described the creation process to the Atlantic by saying, “You put water in a tank. You stir the stuff in[to] the tank.” That stuff is largely oil, but since oil and water don’t mix, that stuff is also emulsifiers, which blend the two so skin care doesn’t go the way of balsamic vinaigrette.

Oil- and wax-based elixirs — the exceptions to the water rule — can’t absorb past the skin’s surface, either. These molecules are simply too big. Oils specifically “have these huge lipid complexes that are basically, you know, congealed,” says Greg Altman, Ph.D., the founder of chemistry company Evolved by Nature and beauty brand Silk Therapeutics. “They make the skin feel great, but the chance that they’re going into the body is, in my opinion, slim.” Waxes and balms have an even slimmer chance of breaking through the barrier, as they are “enormous.” Silicones have almost no hope of absorption at all; they coat the skin in what’s essentially a plastic film — the Saran Wrap of skin care.

That’s not to say some of these non-penetrative ingredients aren’t lovely. “They can seal the skin and give a hydrating effect, and when you do that, then everything happening underneath is very happy,” explains Dr. Altman. The whole point of skin care, really, is to nourish the skin barrier. Once that’s good, the skin’s “normal regenerative processes take over,” the chemist says. It self-moisturizes (via sebum), self-exfoliates (via a shedding process known as desquamation), self-protects (via the acid mantle, which neutralizes invading bacteria and pathogens), and self-heals.

“But my skin care feels like it’s ‘sinking in,’” you may protest, as I did. This is an illusion. That sinking-in sensation — moisturizer melting into your face, going from wet to less-wet in minutes — is merely air-drying in action. Sure, some of the external hydration products provide is absorbed into the skin barrier (did you know dead skin cells hoard moisture? They do!), but the majority of water and water-soluble ingredients, like fragrance and essential oils, start evaporating into thin air as soon as they’re applied.

The rest are “essentially washed off,” per Dr. Altman, although oils and waxes can delay this effect. “Even if you’re not washing your face, throughout the day, you’re sweating, your skin is breathing, there’s humidity in the air, ingredients are getting diluted.” You also lose dead skin cells (the very same ones you applied skin-care to) at a rate of about 40,000 per day. “As you shed dead skin cells you are shedding ingredients from your moisturizer that didn’t penetrate the skin,” Perry Romanowski, a cosmetic chemist and founder of The Beauty Brains, tells the Cut. “The ingredients are ‘lurking’ wherever your dead skin cells are lurking.” The air, your clothes, dust bunnies. (Very dewy dust bunnies.)

Even ingredients that naturally occur within the skin are destined for a surface-level existence. Collagen protein, for example, lives in the dermis, a lower layer of the skin — but topical versions can’t magically woosh down to the dermis. “Protein that is larger than 50 kilodaltons has no chance of ever penetrating the skin,” Dr. Altman says. The same goes for hyaluronic acid, or HA, another natural dermis-dweller. “There are no hyaluronic acids that can actually transport and penetrate the skin,” he states. “That is why we have the world of injectable dermal fillers.” (HA absorbs up to 1,000 times its weight in water, and since cosmetic-grade HA is a powder that needs to be dissolved in water, HA absorbs a portion of its potential water weight from within its very own skin-care formulation. By the time those HA molecules hit your water-resistant skin barrier, they’re already heavy with — sigh — water. Low molecular weight HA can slightly penetrate, but most of it doesn’t.)

The skin-care savvy have found a way around this, though. According to the chemist, “The reality is if you want to open up the skin, you have to decrease the pH of the stratum corneum, which makes the skin more porous.” You can do it with exfoliators, like acids and chemical peels, or you can do it with energy, like lasers. Formulators even incorporate ingredients that break down the barrier, like alcohol, to aid in product penetration, which is not necessarily advisable. “We don’t put things in pores,” says an exasperated-sounding Dr. Altman. They are, he points out, outgoing channels for sweat and sebum. “Any time we put things in pores, we end up in trouble. That’s where we get acne.”

However, if an ingredient checks all the right boxes — hydrophilic and lipophilic properties, a low molecular weight — it can safely sneak past the stratum corneum without clogging the pores. Vitamin C is one such substance; it travels to the dermis (and maybe even deeper) to stimulate natural collagen production. Epidermal Growth Factor (EGF) supposedly absorbs this way, too. “We just discovered a silk molecule that is of the right size that has the ability to both penetrate the skin and cause skin cells to produce more collagen,” adds Dr. Altman. It’s called Activated Silk 27C. (A synthesized version of EGF from baby foreskin was the star ingredient in the “penis facial” loved by the Ocean’s Eight cast). The catch: If any of these are ensconced in silicone, they probably won’t pierce the surface.

Finally, there are the beauty ingredients that beat all the odds; that infiltrate both the circulatory and lymphatic systems. (Dr. Altman describes the two as different lanes in the same underground tunnel where, “unlike Boston Logan,” changing lanes is allowed. Whatever ends up in the blood ends up in the lymph and vice versa.)

To achieve this feat of absorption, molecules need to be very small, oil-soluble (to break through the skin barrier), and water-soluble (to break through the blood barrier). This does not make them any better at skin care. “The goal is to create products that work on the skin’s surface, not to absorb into your blood,” as Robinson puts it. Especially because the Food & Drug Administration classifies blood-penetrating ingredients as “drugs.”

Here’s where skin care gets a little suspicious. “The one regulation that the FDA does have is, you cannot make structural or functional claims with a particular ingredient,” Dr. Altman says. “So let’s just say you have an ingredient in your formula that does penetrate, you would be in violation of FDA regulations if you actually said that.” This is likely because salable “drugs” need to ensure consumer safety … and no one really knows what blood-penetrating beauty ingredients do once they’re in the body. Take chemical sunscreens. The FDA recently found that six of them — avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate — not only absorb directly into the bloodstream, but they do so at “toxic” levels. What does that mean for human health? No idea! “Further studies” are needed “to determine the clinical significance of these findings.”

Other blood-surfing skin-care ingredients include retinol (it’s listed on California’s Prop 65 for potential “reproductive toxicity” for this reason), sodium lauryl sulphate (or SLS, found in cleansers), and polycyclic aromatic hydrocarbons (aka PAHs, possible contaminants in petrolatum and mineral oil and suspected carcinogens). A study from 2009 found over 200 additional chemicals in infants’ umbilical cord blood, some from beauty products presumably worn by their mothers.

“Some of these chemical molecules actually look like hormones, and then the blood system distributes them throughout the body,” Dr. Altman elaborates. Parabens (a preservative), phthalates (maybe hidden in fragrance), butoxyethanol and methoxydiglycol (both glycol ethers), and the aforementioned octinoxate all fall into this category. Studies show they may mess with fertility and sexual function, and even contribute to hormone-related cancers like breast cancer. Parabens specifically have been found in breast tissue and breast tumors. “Recent data points to parabens’ potential to cause harm,” Robinson confirms, but again, “more research is needed” to determine the extent of said harm. recommends avoiding parabens and phthalates altogether, just in case.

The real questions, Dr. Altman says, are these: Where does all the skin care go after it’s in the body? Is it filtered out by the liver, only to be reabsorbed with the next nighttime routine? Could chronic chemical exposure from cosmetics have long-term health implications? “In truth, this is not an area in which scientists have done much research,” Romanowski agrees. “The topic of the life cycle of ingredients … has not been investigated.”

While the world waits for answers, find comfort in the fact that most skin-care will vanish into thin air before it ever makes it to your veins.

Where Does All the Skin Care Go?