The trend and flared pants, a few years a cycle, cosmetics "brush acid" is actually more than 20 years ago Avon's invention, "brush acid", can treat pigmentation, acne, photoaging and other skin problems, the mechanism is clear, the effect is clear, short and fast, loved by young consumers, with rapid effect is not ambiguous, sitting firmly in the beauty industry this year's "top stream".
From a book
Under the background of the "brush acid" fever, skin care brands have laid out the "brush acid" product line, and the skin care products with "acid" as the main effect and claim are also endless. However, in the context of competitive "inner volume", in order to seek a photogenic circle, rely on stacking "strong drugs" to attract consumers' attention, and ignore the use of acid-containing skin care products with high concentration, high frequency and high acidity, which may lead to sensitive skin, which leads to a mixture of acid-containing products in the skin care product market, and it is difficult for ordinary consumers to find the efficacy and safety of brush acid products.
After the Food and Drug Administration monitored the risk, it quickly gave a risk reminder, and on August 11, it gave the popular science article "scientific understanding" of brushing acid "beauty", which is a reminder to the industry, and at the same time reminds consumers that "brushing acid needs to be cautious".
The "brush acid treatment" mentioned in the Food and Drug Administration's popular science article, professionally speaking, does not actually belong to the field of cosmetics, it needs to be operated by trained professionals in hospitals or clinics with medical qualifications, and the "acid" used is too risky and cannot be used in cosmetics, such as: tretinoin, trichloroacetic acid, etc., they are prohibited ingredients in cosmetics. These should only be used in medical settings under the prescription and supervision of a doctor.
"Brushing acid" requires caution, but it does not mean that all acid-containing skin care products should be beaten to death. It is undeniable that the low concentration of acid-containing products, mainly acting on the stratum corneum of the skin, has a clear effect on improving acne closure, delicate skin texture, removing blackheads, tightening pores, etc., and is recognized as an effective means in the skin care industry. Consumers do not need to treat it as a flood beast, as long as they can correctly recognize the efficacy that acid-containing skin care products can achieve, avoid blindness, and learn better "daily brush acid, safe brush acid, legal brush acid", you can get benefits from acid-containing skin care products.
Acids commonly used in cosmetics
α-Hydroxy Acid (AHA)
α-hydroxy acid α-carbon hydrogen is substituted by hydroxyl groups of carboxylic acids, because most of them occur naturally in fruits, so they are called fruit acids. From a structural point of view, the commonly used fruit acids in cosmetics include: glycolic acid (hydroxyacetic acid), lactic acid, malic acid, tartaric acid, bitter amygdalic acid (mandelic acid), glucoic acid, citric acid, lactic acid, maltoseic acid, etc. (sorted by molecular weight from small to small). It should be understood that the above fruit acids now used in the cosmetics industry are synthetic and not extracted from fruits.
The latest N-acetyl neurine approved by the NmPA, commonly known as "bird's nest acid", also belongs to α-hydroxy acid.
The first generation of fruit acids is represented by hydroxyacetic acid, which is a water-soluble acid with relatively small molecular weight and strong permeability. The fruit acid in cosmetics accelerates the loosening and shedding of cuticle cells on the surface of the skin through acid stimulation, which has the effect of promoting metabolism and stripping away old waste keratin. Therefore, it can alleviate the dullness of the face and rough skin caused by the thickness of the old waste keratin; accelerate the metabolism of melanin gathered in the keratinocytes, evenly brighten; remove the dead cells that are ineffective at the opening of the sebaceous glands, avoid the pores from being blocked by sebum, and improve the growth of acne [1].
The second generation of fruit acids is gluconolactone (gluconic acid δ lactone), which does not work by itself. However, when the formula contains water, it will hydrolyze and open the ring to form glucoic acid. Gluconic acid has a large molecular weight, is much less irritating than the first generation of fruit acids, and has a stronger moisturizing ability because it contains more hydroxyl groups. In addition, gluconolactone/glucohydrate exhibits superior antioxidant properties compared to AHA [2] and significantly enhances stratum corneal barrier function with less transcutaneous water loss (TEWL).
In the "2021 Edition of the Catalogue of Used Cosmetic Raw Materials", the maximum use of gluconolactone in resident products is 15%, but the industry understands that the maximum use of the "Catalogue of Used Cosmetics Raw Materials 2021 Edition" is only a transitional plan and does not have a rigorous scientific nature. Therefore, I personally believe that according to the current regulations, if it is in an anhydrous formula, the maximum amount of gluconolactone can be used is 15%, but if the formula contains water, considering the inevitable formation of glucuronic acid, it should still comply with the use of fruit acid restrictions.
The third generation of fruit acids are lactose acid and maltoseic acid (maltoclic acid, which is not currently in the "2021 Used Raw Materials Catalog"), which is a polyhydroxybial acid, which is manifested as a stronger binding water ability and excellent antioxidant ability than glycerin, reducing light damage to the skin, and can show significant anti-aging effects [2].
New Raw Material Filing No. 1: Sialic Acid:
2% sialic acid pH is 1.8-2.3, which is theoretically a good choice for brushing acid. However, the state stipulates that the maximum amount of cosmetics added is 2%. This new ingredient has moisturizing properties and multiple skin care functions, and is expected to become a multi-functional brush acid upstart in the future.
β-Hydroxy Acid (BHA)
β-hydroxy acid is a carboxylic acid in which β-carbon hydrogen is substituted by a hydroxyl group, and its representative substance is salicylic acid. Salicylic acid is a fat-soluble acid, in cosmetics, salicylic acid mainly improves acne in three ways: 1, unclogging pores, loosening the angle plug; 2, effective bacteriostatic; 3, control inflammation.
Salicylic acid has many derivatives, and caprylyl salicylic acid is the most famous. The miracle drug aspirin, which is also the most famous derivative of salicylic acid - acetylsalicylic acid.
Azelaic acid
In addition to the above two types of acids, azelaic acid is also widely used in cosmetics. Azela, also known as rhododendron acid, is a naturally occurring dibasic acid (the molecular backbone is no hydroxyl group), which is generally used in whitening and acne removal cosmetics. It can effectively inhibit bacteria and oil control, and also prevent the formation of melanin, reduce melanin concentration, and prevent spot formation. Azeric acid can not only make the pigmentation lesion lighter, but also reduce the extent of the lesion [2]. Usually azelaic acid is well tolerated, can be used for a long time, and skin irritation and phototoxicity are rare [3].
In fact, there are thousands of types of acids available in cosmetics, and these ingredients mentioned above are only widely used in the current "brush acid" cosmetics.
HEPES Isethionine ethanesulfonic acid
This ingredient is a very good acid-base buffer for cell culture, studies have proved to have a certain softening keratin function, it is soluble in water, its pH value is between 6-8, not a brush acid.
vitamin C
Vitamin C, also a lactone, is soluble in water, its molecule in the 2nd and 3rd positions on the two adjacent enol hydroxyl groups, very easy to dissociate and release hydrogen ions, with acid properties, so also known as ascorbic acid, with the properties of monobasic acid (the molecular backbone is no hydroxyl).
The pH of 0.5% aqueous vitamin C solution is about 3, and the pH of 2% aqueous solution is 2.4-2.8, which is also a relatively strong acid. Vitamin C is acidic and reductive, theoretically with a high concentration of prototype vitamin C can also brush acid, but also has a clear whitening effect, but vitamin C is extremely unstable in water, so the high content of prototype vitamin C for brushing acid, there is difficulty in the formula.
The current regulations regulate "acids" in cosmetics
The "Cosmetic Safety Technical Specification" has the following clear requirements for the addition of α-hydroxy acid and salicylic acid in cosmetics:
Requirements for α-hydroxy acids:
Since α-hydroxy acid has a certain decormination effect, and its decortication force is related to concentration and pH, the "Cosmetic Safety Technical Specification" mainly controls α-hydroxy acid from two aspects, one is the content, and the other is pH. The total amount of α-hydroxy acid in cosmetics must be ≤6%, and in addition to the shampoo products, the pH of the product ≥ 3.5, and it should be emphasized that even the washed mask should meet the pH ≥ 3.5 requirements. In addition, the regulations also require that in non-sunscreen skin care cosmetics, when the content of α-hydroxy acid ≥3% or the label declares α-hydroxy acid, it should be marked on the label "used in conjunction with sunscreen cosmetics".
Requirements for Salicylic Acid:
When salicylic acid is not used as a preservative in the formulation, the Cosmetic Safety Technical Specifications mandate that the maximum content of salicylic acid in resident products and leaching skin care products is 2%, and the maximum amount of salicylic acid added in shower hair products is 3%. Except for shampoos, it should not be added to products used by children under three years of age, and the purpose of salicylic acid use and the words "Salicylic acid: do not use for children under three years of age" must be indicated on the label.
When salicylic acid is used as a preservative, the maximum added amount is only 0.5%.
As a friendly reminder, any kind of α-hydroxy acid containing any content, according to the provisions of the drug supervision, as long as the pH value is lower than 3.5, it is suspected of violating the current regulations. In particular, hydrolytically equilibrated products such as glucarolactones are added, and the pH of such products will drift, which is very difficult to control its pH range, and requires a mature buffer system and long-term stability observation.
How to choose cosmetics containing acids
It must be remembered that cosmetics are not medicine!
And there is no magic medicine for "one night rejuvenation" in the current world!
We do not recommend acid-containing skin care products for sensitive skin,
1. Pay attention to the concentration
If it is a daily maintenance product, it is recommended to choose cosmetics with a content of α-hydroxy acid below 6%, and a salicylic acid content of less than 2% and a PH higher than 3.5. The blind pursuit of high concentrations is accompanied by an increased chance of irritation, allergies, and skin damage.
2. Pay attention to pH
The smaller the pH, the more potent the acid ingredients are, but the more irritating they become. If you only look at the concentration of acid ingredients, it is unreasonable to evaluate the efficacy of the product by putting aside the pH value of the product. When choosing an acid-containing product, you should combine your own skin condition and tolerance and choose a product with a pH in the range of 3.5 to 4.5. Products with too high a pH do not have the benefits and efficacy that brush acid is expected to bring.
The frequency of brushing acid should not be too high, and it is recommended to use brush acid products 1-2 times a week.
3. Pay attention to the brand
Compared with small brands, the research and development strength of large brands is relatively stronger, and the formula can be scientifically designed according to product positioning, and its complete safety and efficacy verification system is usually tried by consumers (human body) to ensure that after the product is listed, the probability of stimulation is greatly reduced, and ordinary consumers are more assured.
Instructions for use of cosmetics containing acids
After use, the skin is slightly tingling and itchy, and brush acid products are common, which is a normal skin reaction. Consumers who have a more severe reaction must stop using it for a period of time and try it again after the skin has recovered. Sensitive consumers are recommended to apply a moisturized soothing cream before brushing acid, or directly choose a highly moisturized brush acid cosmetic to buffer irritation.
Slight local peeling, which is also normal, moisturize and moisturize during the period, if the peeling is more serious, it is recommended to stop for a period of time, and try again after the skin recovers. Short-term acne on the skin after the use of brush acid products is also normal, which is the reaction of the skin after being stimulated, if the acne situation continues to be serious, it means that the skin is intolerant, and other types of acne products need to be selected.
Brush acid products should be used at the same time, avoiding the use of strong drug type cosmetics. It is recommended to use cosmetics that have a gentle soothing and moisturizing effect, or products with high ceramide content to help the skin rebuild the barrier. Products with mild whitening effects can be used, but avoid products with high levels of whitening agents to avoid irritation. After brushing acid, the newborn skin is delicate, try to avoid brushing acid on days with strong summer sunshine, and the skin is prone to allergies in spring, so brush acid as much as possible in autumn and winter.
Needless to say, acid itself is a class of excellent skin care ingredients, there is indeed no shortage of acid-containing cosmetics on the market that can really solve skin problems, but consumers can not be blind, or need to be rational, cautious, and individually choose and use conscientious products that meet the regulations. I also hope that the majority of peers can uphold the attitude of being responsible for consumers and develop truly safe and effective acid-containing cosmetics!
Remember, daily brush acid twice a week acid / effective brush acid rely on brand reputation / legal brush acid product pH can not be less than 3.5