Thursday, November 17, 2005
AHAs vs. BHA
There are two primary topical ways to exfoliate skin, either with alpha hydroxy acids (AHAs), or with beta hydroxy acid (BHA). There is only one BHA (beta hydroxy acid) and that is salicylic acid, but there are a variety of AHAs. The five major types of AHAs that show up in skin-care products are glycolic, lactic, malic, citric, and tartaric acids. Of these, the most commonly used and most effective AHAs are glycolic and lactic acids. Both of these have the ability to penetrate the skin, plus they have the most accumulated research on their functionality and benefit for skin.
What glycolic, lactic, and salicylic acids both do is "unglue" the outer layer of dead skin cells, allowing healthier cells to come to the surface. Removing this dead layer can improve skin texture and color, unclog pores, and allow moisturizers to be better absorbed by the skin. Both AHAs and BHA affect the top layers of skin, and they help to improve the appearance of sun-damaged, dry, and/or thickened skin. Sun damage in particular causes the top layer of skin to become thicker, creating a dull, rough appearance on the surface of skin.
The primary difference between AHAs and BHA is that AHAs are water-soluble, while BHA is lipid-(oil) soluble. This unique property of BHA allows it to penetrate the oil in the pores and exfoliate accumulated skin cells inside the oil gland that can clog pores. BHA is best used where blackheads and blemishes are the issue, and AHAs are best for sun-damaged, thickened, dry skin where breakouts are not a problem.
AHAs work best at concentrations of 5% to 10% with a pH of 3 to 4, and their effectiveness diminishes as you go above a pH of 4.5. BHA works best at concentrations of between 1% and 2%, and at an optimal pH of 3, diminishing in effectiveness as you go past a pH of 4. Both AHAs and BHA lose their effectiveness as a product's pH goes up or the concentration of the ingredient goes down.
It is interesting to not that at any pH, AHAs provide the added benefit of helping to keep water in the skin at the same time that exfoliation is taking place. This is due to the way they affect skin cells adding increased protection. AHAs can also increase the production of ceramides in the skin, which help keep it moist and healthy.
AHA and BHA products can definitely smooth the skin, fade signs of sun damage, correct uneven skin tone, improve texture, unclog pores, and give the appearance of plumper, firmer skin (because more healthy skin cells are now on the surface). Unfortunately, they have no residual effect—when you stop using them the skin will go back to the condition it was in before you started.
Retinoids (Retin-A, Differin, and Tazorac)
Let me make it perfectly clear that retinoids are not exfoliants, though many people think that’s what they do. Retinoids are a general term referring to a vast range of ingredients derived from vitamin A. Prescription-only, topically applied retinoids are significant for skin because they can positively affect the way cells are formed deep in the dermis.
If you have sun-damaged, dry, wrinkled, or acne-prone skin, you should become familiar with the names Retin-A, Renova, Differin, Avita, and Tazorac, which all contain different forms of retinoids. The active ingredient in Retin-A, Avita, and Renova is tretinoin, Differin uses adapalene, and Tazorac uses tazorotene. In fact, both Renova and Tazorac have been approved by the FDA for the treatment of wrinkles.
Exfoliants such as AHAs and BHA primarily affect the surface of the skin (epidermis) or the lining of the pore by actually ungluing or dissolving layers of skin cells. In contrast, retinoids affects the lower layers of skin (dermis), where new skin cells are produced. Retinoids actually communicate with a skin cell as it is being formed, telling it to develop normally instead of developing as a sun-damaged or genetically malformed skin cell.
Why the confusion about the effect retinoids can have on the skin? Primarily it’s due to the fact that products containing retinoids can cause irritation and inflammation, resulting in the skin becoming flaky and dry. This flaking and dryness is not exfoliation, nor is it a desirable or advantageous result. If retinoids cause your skin to be consistently dry and flaky, it is a problem and you should probably avoid products that contain it or reduce how often you use them.
Despite the valuable effect retinoids can have for skin, don’t expect retinoids to erase wrinkles because they are not a wrinkle cure. However, if skin cells can be produced with a healthier form and shape, the surface of skin will have a smoother appearance, skin cells will do their job of turning over in a more normal fashion, the protective outer layer of skin will remain intact, enhancing the skin’s healing response, and on and on. In essence, the skin will behave and look the way it did (to some extent) before it was damaged by the sun.
Regardless of these positive effects, retinoids will be useless, and the skin will be prone to more damage, if you do not wear a sunscreen as well. Not a wrinkle cream in the world, even one approved by the FDA, can have positive results if you don’t use an effective sunscreen; without that, you are just adding to damage you already have accumulated.
What retinoids, AHA, and BHA products have in common is that once you stop using them, your skin will revert to the way it was before. These products will not produce permanent change. The smooth exterior lasts only as long as you use them. But used together long-term, they are a formidable weapon in the battle against wrinkles and blemishes.
What glycolic, lactic, and salicylic acids both do is "unglue" the outer layer of dead skin cells, allowing healthier cells to come to the surface. Removing this dead layer can improve skin texture and color, unclog pores, and allow moisturizers to be better absorbed by the skin. Both AHAs and BHA affect the top layers of skin, and they help to improve the appearance of sun-damaged, dry, and/or thickened skin. Sun damage in particular causes the top layer of skin to become thicker, creating a dull, rough appearance on the surface of skin.
The primary difference between AHAs and BHA is that AHAs are water-soluble, while BHA is lipid-(oil) soluble. This unique property of BHA allows it to penetrate the oil in the pores and exfoliate accumulated skin cells inside the oil gland that can clog pores. BHA is best used where blackheads and blemishes are the issue, and AHAs are best for sun-damaged, thickened, dry skin where breakouts are not a problem.
AHAs work best at concentrations of 5% to 10% with a pH of 3 to 4, and their effectiveness diminishes as you go above a pH of 4.5. BHA works best at concentrations of between 1% and 2%, and at an optimal pH of 3, diminishing in effectiveness as you go past a pH of 4. Both AHAs and BHA lose their effectiveness as a product's pH goes up or the concentration of the ingredient goes down.
It is interesting to not that at any pH, AHAs provide the added benefit of helping to keep water in the skin at the same time that exfoliation is taking place. This is due to the way they affect skin cells adding increased protection. AHAs can also increase the production of ceramides in the skin, which help keep it moist and healthy.
AHA and BHA products can definitely smooth the skin, fade signs of sun damage, correct uneven skin tone, improve texture, unclog pores, and give the appearance of plumper, firmer skin (because more healthy skin cells are now on the surface). Unfortunately, they have no residual effect—when you stop using them the skin will go back to the condition it was in before you started.
Retinoids (Retin-A, Differin, and Tazorac)
Let me make it perfectly clear that retinoids are not exfoliants, though many people think that’s what they do. Retinoids are a general term referring to a vast range of ingredients derived from vitamin A. Prescription-only, topically applied retinoids are significant for skin because they can positively affect the way cells are formed deep in the dermis.
If you have sun-damaged, dry, wrinkled, or acne-prone skin, you should become familiar with the names Retin-A, Renova, Differin, Avita, and Tazorac, which all contain different forms of retinoids. The active ingredient in Retin-A, Avita, and Renova is tretinoin, Differin uses adapalene, and Tazorac uses tazorotene. In fact, both Renova and Tazorac have been approved by the FDA for the treatment of wrinkles.
Exfoliants such as AHAs and BHA primarily affect the surface of the skin (epidermis) or the lining of the pore by actually ungluing or dissolving layers of skin cells. In contrast, retinoids affects the lower layers of skin (dermis), where new skin cells are produced. Retinoids actually communicate with a skin cell as it is being formed, telling it to develop normally instead of developing as a sun-damaged or genetically malformed skin cell.
Why the confusion about the effect retinoids can have on the skin? Primarily it’s due to the fact that products containing retinoids can cause irritation and inflammation, resulting in the skin becoming flaky and dry. This flaking and dryness is not exfoliation, nor is it a desirable or advantageous result. If retinoids cause your skin to be consistently dry and flaky, it is a problem and you should probably avoid products that contain it or reduce how often you use them.
Despite the valuable effect retinoids can have for skin, don’t expect retinoids to erase wrinkles because they are not a wrinkle cure. However, if skin cells can be produced with a healthier form and shape, the surface of skin will have a smoother appearance, skin cells will do their job of turning over in a more normal fashion, the protective outer layer of skin will remain intact, enhancing the skin’s healing response, and on and on. In essence, the skin will behave and look the way it did (to some extent) before it was damaged by the sun.
Regardless of these positive effects, retinoids will be useless, and the skin will be prone to more damage, if you do not wear a sunscreen as well. Not a wrinkle cream in the world, even one approved by the FDA, can have positive results if you don’t use an effective sunscreen; without that, you are just adding to damage you already have accumulated.
What retinoids, AHA, and BHA products have in common is that once you stop using them, your skin will revert to the way it was before. These products will not produce permanent change. The smooth exterior lasts only as long as you use them. But used together long-term, they are a formidable weapon in the battle against wrinkles and blemishes.
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