As a growing amount of research has looked into what causes wrinkles and the effects of photoaging, the use of beta hydroxy acid has increased greatly in popularity. There are two types of hydroxy acids: alpha and beta. Alpha hydroxy acids (AHA) are exfoliants that are derived from fruit and milk sugars such as glycolic acid, which is produced from sugar cane and lactic acid (which is produced from milk). There is only one beta hydroxy acid (BHA) commonly used in skin care products, and that is salicylic acid,﻿﻿ which is derived from aspirin.

How Beta Hydroxy Acid Works

Beta hydroxy acid works mainly as an exfoliant. It causes the cells of the epidermis (the outermost layer of the skin) to become "unglued," allowing the dead skin cells to slough off, making room for the regrowth of new skin. Beta hydroxy acid is reported to improve wrinkling, roughness, and mottled pigmentation of photodamaged skin after at least six months of daily application. Beta hydroxy acid that's found in skincare 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-soluble, meaning it will dissolve in oil. This means that beta hydroxy acid is able to penetrate into the pore, which contains oily sebum and exfoliate the dead skin cells that build up inside the pore. Due to this difference in properties, beta hydroxy acid is better used for oily skin with blackheads and whiteheads.﻿﻿ Alpha hydroxy acids are better used on thickened, sun-damaged skin where breakouts are not a problem.

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 who is using beta hydroxy acid must use a good sunscreen that contains UVA and UVB protection.

Watch out for Skin 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. 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 best. Cleansers containing beta hydroxy acid are not very effective because the beta hydroxy acid must be absorbed into the skin to work. Cleansers are washed off before this absorption occurs.

There are no effective products that combine beta hydroxy acid and sunscreen because sunscreen is not stable at the pH that's required to make the beta hydroxy acid effective. Sunscreen must be applied liberally when using a beta hydroxy acid product. The sunscreen should have an SPF of at least 15 for UVB protection (ideally 30 or higher) 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 include pH information on the label. The only way to know the pH of a product is to test it with a pH strip.

Unlike alpha hydroxy acid, which must be listed in the top three ingredients to indicate the appropriate concentration, beta hydroxy acid can be listed in the middle or even toward the bottom of the ingredient list because it is effective at lower concentrations.