Hydroxy acids can be available in two basic types – alpha & beta hydroxy acids. These hydroxy acids help in reducing discoloration of the skin, improving acne, perfecting face lines and giving the skin a radiant and healthy glow. For these reasons, they are commonly used in skin care products. Alpha hydroxy acids also known as AHA are a collective of compounds which have been in use to make the skin fresh thousands of years ago. One example is that Cleopatra uses sour milk for bath.

What Is Beta Hydroxy Acid?

Beta hydroxy acid belongs to a family of organic acids and is not a single substance. These beta hydroxy acids can be found naturally or can be made synthetically. The naturally occurring ones are found in the body, in fruits and in the bark of the willow tree.

These acids have been synthesized in the labs by scientists and it has been proven that they are as effective as the ones found naturally. For this reason they are used in various medicines and other commercial products. The various acids which are a part of the beta hydroxy acid family are salicylic acid, beta-hydroxybutyric acid, 3-hydroxypropionic acid, beta-hydroxy beta-methylbutyrate acid and carnitine.

The main mode of action of beta hydroxy acid is by causing exfoliation of the skin. The dead skin cells from the epidermis are removed and slough off, thus allowing the regrowth of new skin. It helps in improving the fine lines, wrinkles, roughness in skin and mottled pigmentation in photo damaged skin. The effects are seen after daily use for at least 6 months. Skin caring products contain beta hydroxy acid in concentration of 1% to 2% and at pH of 3 to 4.

Alpha Hydroxy Acid vs. Beta Hydroxy Acid

Difference between Alpha & Beta Hydroxy Acids

A layperson might not understand the subtle difference between the alpha & beta hydroxy acids. They both are chemical compounds made up of carboxylic acid and hydroxyl group. The location of the hydroxyl group determines the type of acid. Due to the difference in location of the hydroxyl group, alpha hydroxy acids are water soluble and beta hydroxy acids are oil soluble.

• Alpha Hydroxy acids act on the top most layer of the skin, since they are water soluble. They help in removal of the dead skin cells, promote the production of new skin cells. For this reason, they are more effective on old and thick skin, especially sun-damaged one.
• Beta hydroxy acids: Salicylic acid is a type of beta hydroxy acid. Since it is soluble in oil, it penetrates the skin pores which are filled with oil and help in breaking down the dead skin cells present inside the pores. For this reason, it works best on oily skin.

Which One to Choose – AHA or BHA?

For dry and damaged skin, alpha hydroxy acids should be used; for acne problems on younger and oily skin, beta hydroxy acids should be used.

How to Use Beta Hydroxy Acid

Various skin care products like moisturizers, cleansers, eye cream, sun-screens and foundations contain beta hydroxy acid. Given below are some pointers when using beta hydroxy acid:

1. Choose a product containing beta hydroxy acid preferably an exfoliant. Then apply other products or cosmetics without containing BHA, to reduce the risk of skin irritation.
2. Use a moisturizer containing beta hydroxy acid is a combination considered the best.
3. The beta hydroxy acid needs to be absorbed by the skin effectively; however, it is not very effective if it present in face cleansers. The cleanser gets washed off before absorption.
4. Beta hydroxy acid is effective only at a certain pH. Beta hydroxy acid is most effective at a pH of 3 to 4 in a concentration of 1-2%. Sunscreens are not stable at this pH; hence there are no products currently available which have beta hydroxy acid in a sunscreen.
5. Different from that alpha hydroxy acid needs to be listed in the top three ingredients in a product, beta hydroxy acid is effective even at lower concentrations, it can be mentioned in the middle or lower in the list. The pH level of the cosmetics is not mentioned on the label, as it is not required by law. It can only be determined by checking with a pH strip.

Precautions

FDA advises that precautions should be taken when using products containing AHAs & BHAs. Some of the precautions are given below:

• Any product containing BHA should be tested on a small area of skin before applying on a larger surface. In case of skin irritation or prolonged stinging, the product should be discontinued immediately and the doctor should be consulted.
• All instructions mentioned on the label should be followed and the product should not be used more times than mentioned.
• Products containing BHA should not be used on children and infants.
• If a BHA containing product is used, a sun protection product should also be applied along with it.

Note: Salicylic acid is not a true BHA from the point of view of a chemist; however, it is referred to as BHA by cosmetic companies. This can lead to consumers also considering it a BHA.