With increasing research into what causes wrinkles and the effects of photoaging, the use of hydroxy acids has increased greatly in popularity. There are two types of hydroxy acids - alpha and beta. Alpha hydroxy acids are exfoliants derived from fruit and milk sugars such as glycolic acid produced from sugar cane and lactic acid produced from milk. There is only one beta hydroxy acid - salicylic acid.
How Beta Hydroxy Acid Works
Beta hydroxy acid works mainly as an exfoliant. It causes the cells of the epidermis to become "unglued" allowing the dead skin cells to slough off, making room for regrowth of new skin. Beta hydroxy acid is reported to improve wrinkling, roughness, and mottled pigmentation of photodamaged skin after at least 6 months of daily application. Beta hydroxy acid found in skin-care products works best in a concentration of 1% to 2% and at a pH of 3 to 4.
The Difference Between Alpha and Beta Hydroxy Acids
The main difference between alpha hydroxy acids and beta hydroxy acid is their lipid (oil) solubility. Alpha hydroxy acids are water soluble only, while beta hydroxy acid is lipid (oil) soluble. This means that beta hydroxy acid is able to penetrate into the pore which contains sebum and exfoliate the dead skin cells that are built up inside the pore. Because of this difference in properties, beta hydroxy acid is better used on oily skin with blackheads and whiteheads. Alpha hydroxy acids are better used on thickened, sun-damaged skin where breakouts are not a problem.
Beta Hydroxy Acid and Sun Sensitivity
The use of beta hydroxy acid can increase sun sensitivity by 50% causing an interesting dilemma. It appears that beta hydroxy acid may be able to reverse some of the damage caused by photoaging, but at the same time it makes the skin more susceptible to photoaging. It is clear that anyone using beta hydroxy acid must use a good sunscreen that contains UVA and UVB protection.
Beta Hydroxy Acid and Irritation
Beta hydroxy acid appears to be less irritating than alpha hydroxy acid even though it penetrates deeper into the pore. This occurs because salicylic acid is derived from acetylsalicylic acid, or aspirin. Aspirin has anti-inflammatory properties, and salicylic acid retains many of these anti-inflammatory properties. Despite this fact, beta hydroxy acid can still cause skin irritation. Symptoms of irritation include redness, burning, itching, pain, and possibly scarring. People with darker colored skin are at a higher risk of scarring pigment changes with beta hydroxy acid.
Using a Beta Hydroxy Acid
Beta hydroxy acid is found in a variety of skin care products including moisturizers, cleansers, eye cream, sunscreen, and foundations. Here are some guidelines to use when trying to decide which hydroxy acid formulation to use:
- It is best to pick one product that contains the proper formulation of beta hydroxy acid to use as your exfoliant, and then choose other skin care products or cosmetics that don't contain hydroxy acids to reduce the likelihood of skin irritation.
- Using beta hydroxy acid in a moisturizer base may be the best combination of products.
- Cleansers containing beta hydroxy acid are not very effective because the beta hydroxy acid must be absorbed in the skin to work. Cleansers are washed off before this absorption occurs.
- At this time there are no effective products that combine beta hydroxy acid and sunscreen, because sunscreen is not stable at the pH required to make the beta hydroxy acid effective.
- Sunscreen MUST be applied liberally when using an alpha hydroxy acid product. The sunscreen should have an SPF of at least 15 for UVB protection and contain avobenzone, titanium dioxide, or zinc oxide for UVA protection.
- Beta hydroxy acid works best in a concentration of 1% to 2% and at a pH of 3 to 4.
- Unfortunately, cosmetic manufacturers are not required to pH information on the label. The only way to know for sure the pH of a product is to test with a pH strip. Paula Begoun has done this in her skin care product reviews found in her book "Don't go to the Cosmetics Counter Without Me."
- Unlike alpha hydroxy acid that must be listed in the top 3 ingredients to indicate the appropriate concentration, beta hydroxy acid can be listed in the middle or even towards the bottom of the ingredient list because it is effective at lower concentrations.