In the field of skin care, formulators love alcohol as much as smokers love tobacco. That's really, it's hard not to come.
From sunscreen and toner to essence and eye cream, we can all see the high or low position in the ingredient list.
Tip 1。 Denatured ethanol is also an ethanol additive. This operation is to prevent illegal traders from purifying the alcohol in the ingredients and then reselling it into edible alcohol.
Tip 2. Have you ever heard that people who fight during prohibition drink shampoo? That's really delicious.
Some people like to add, while others aim at it. We see that many alcohol-free/alcohol-free skin care products are marketed for it.
So why do you like to add alcohol to skin care products? Will it cause harm to the skin?
1. Functions and uses of alcohol in cosmetics
dissolution
Ok, this is a chemistry problem.
As we know, the most common solvent is water. But many ingredients are insoluble in water, so we may change the solvent into oil.
For the simplest example, clothes are stained with paint, and water can't be washed off, but we can solve this problem perfectly by switching to gasoline. Of course, it is impossible to add gasoline to cosmetics, otherwise you want to set yourself on fire or something.
In the same way, many ingredients are insoluble in water and oil, and alcohol can only be used as a solvent for this substance.
After all, many substances are difficult to adapt to cosmetics if they are not dissolved.
Penetration promoter
Ethanol is alcohol, and alcohol itself is a small molecule. You should know that small molecules can quickly pass through the stratum corneum.
At the same time, ethanol has a good affinity with water, so substances dissolved in ethanol can play a role as alcohol slowly penetrates into the stratum corneum.
disinfectant
Alcohol itself has antibacterial effect. When the alcohol content in cosmetics exceeds 10%, the products can basically be self-preserved without adding other preservatives.
Of course, alcohol is rarely seen as an antiseptic product, but it is an important function, which plays a role simultaneously with other functions.
Convergence and coolant
A certain concentration of alcohol can denature protein. If a large amount of alcohol is added to cosmetics, it can dry quickly.
At the same time, alcohol is volatile, which will accelerate the volatilization of alcohol under the action of skin temperature. The liquid gasification process takes away a lot of heat, which makes the skin surface cool.
This is why some cosmetics add a lot of alcohol, because their unparalleled skin experience makes many people want to stop.
For example, the addition of alcohol to healthy water, which was popular before, can rank second in the ingredient list.
2. What are the potential hazards of alcohol to the skin?
Epidermal injury
When introducing the beauty function of alcohol, we mentioned that alcohol can make protein degenerate.
Then when using cosmetics with high alcohol content, it will quickly drain away the moisture on the skin surface, making the stratum corneum hard and dry.
In addition, alcohol has good permeability. If high concentration of alcohol enters the stratum corneum, it will also damage the cells of stratum corneum and dermis, causing indirect and direct damage to the skin barrier function.
If you use toner or other skin care products with high alcohol content on the basis of excessive cleaning, your skin will become fragile and sensitive, and sensitive muscles will not be far away.
Allergic dermatitis
Excessive alcohol concentration will weaken the function of stratum corneum, and at the same time, many substances that would not have caused allergic reactions will become allergic when facing fragile skin, thus causing allergic dermatitis.
Risk of denatured ethanol
Denatured ethanol doesn't sound so direct, but its existence also has inexplicable risks. -CIR expert group, an American expert committee for testing cosmetic ingredients, once made an intriguing judgment: the safety of denatured alcohol depends on what denatured medium is added.
There are many kinds of additives for ethanol denaturation, some of which have been confirmed to be safe, but a large part of the data are incomplete and it is impossible to judge the safety.
In other words, how is alcohol denatured? How much denatured substance was used? Many times we are in an unknown state, and the unknown means risk.
The application of denatured alcohol is often in cosmetics with high alcohol content. ...
Risk+risk =? I won't talk about it later.
3. Can alcohol still be used?
This is just like the problem of acne-causing ingredients in cosmetics we discussed before. Not only the ingredients themselves, but also other factors need to be considered.
Can you use it?
In addition to the influence of the overall formula, if alcohol is only used as a solvent and cosmetics contain a single-digit addition of 1%-2%, the influence of alcohol itself on the overall skin will be minimal.
Even in some products that can be used for sensitive muscles, a small amount of alcohol will be added.
Therefore, the dosage is the key factor to be considered.
Can't use it
However, we must be careful about many cosmetics that contain a lot of alcohol or even alcohol as the main additive.
For example, alcohol is almost one of many products that mainly promote oil control.
But to be honest, alcohol can only improve the problem of skin shine for a short time, and "controlling oil" is completely nonsense.
If you often use cosmetics with high alcohol content, you can refer to the harmful parts of alcohol additives above.
therefore ...
So whether alcohol is harmful to the skin depends on the content and concentration. Although the content of single digits has little effect on the skin, it does not rule out the possibility of other irritation, and ultimately it depends on the skin reaction after trial.
But like those products with high alcohol content, sensitive muscles can be avoided or avoided. People who have no serious skin problems should not use it more. Refer to potential risks.
There is a good advertisement that says: Although XX is good, don't drink too much.
[References]
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[3] Xhauflaire-Uhoda。 E. makarenko E. Denuz. Charlie, C. Pierard, General Electric Company (2008). Skin cream in medical environment: success or evil? Journal of Occupational Medicine and Toxicology.
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[7] Doneko, M., Rishak, E., Galitzka, E., Tyr Likovsky, R., G? Answer? ewsk，E. T。 Przylipiak，A. (20 17)。 Protective effect of hyaluronic acid on focal adhesion kinase activity of human skin fibroblasts exposed to ethanol. Drug design, development and treatment.
[8] F.A. Anderson (2008). Final report on safety assessment of alcohol concentration. , including SD Alcohol 3-A, SD Alcohol 30, SD Alcohol 39, SD Alcohol 39-B, SD Alcohol 39-C, SD Alcohol 40-b and SD Alcohol 40-C, as well as denaturants Quassin, brucine sulfate/brucine and denatonium benzoate/kloc-0. (2008). International Journal of Toxicology.
[9] Robert Baan, Kurt Straif, Yann Grosse, Béatrice Secretan, Fatiha El Ghissassi, Véronique Bouvard, Andrea Altieri, Vincent Cogliano, representing the monograph working group of the WHO International Agency for Research on Cancer. (2007). Carcinogenicity of alcoholic beverages. Policy observation.
Bomannan, d, Potts, R.O. Guy, R. H. (199 1). The effect of ethanol on human stratum corneum was detected by infrared spectroscopy. Journal of controlled release.
Van der Merle, D. Riviere, J. E. (2005). Comparative study on the effects of water, ethanol and water/ethanol mixture on chemical distribution into porcine stratum corneum and silicone rubber membrane. In vitro toxicology.
Pekke, C, Pradalier, A. Fuck, J. (1992). Allergic contact dermatitis caused by ethanol in estradiol transdermal patch. Contact dermatitis.
[13] Ophaswongse, Sh.i. Maibakh (1994). Alcohol dermatitis: allergic contact dermatitis and contact urticaria syndrome. A review. Contact dermatitis.
[14] Rachel Meyer, D. W. (2008). Safety evaluation of local application of ethanol in skin and oral cavity. Journal of Occupational Medicine and Toxicology.
The data in this article was updated on June 5, 2020.
It was originally written by Professor Yang Xichuan, a dermatologist, aiming at popularizing science for readers.
Popular science content can not replace the doctor's diagnosis and treatment advice, for reference only.
If you have skin problems, please consult a doctor in time.
Cover design: Acheng