Alpha and beta hydroxy acids are common ingredients in cleansers, masques, moisturizers and other skin care products. Products containing hydroxy acids can improve skin health and appearance by smoothing rough skin, evening out blotchy pigmentation, reducing the appearance of wrinkles and treating acne. The two types of hydroxy acids are found in plant and milk sugars, but most of the hydroxy acids used in cosmetics are synthetic.
Alpha Hydroxy Acids
There are five major types of alpha hydroxy acids (AHAs). Glycolic acid, the most commonly used, is derived from sugar cane. The others are lactic acid, derived from milk; citric acid, from citrus fruits; malic acid, from apples; and tartaric acid, from grapes. Alpha hydroxy acids are water soluble, meaning they work well on thickened, sun-damaged skin that is not acne-prone.
Beta Hydroxy Acid
There is only one type of beta hydroxy acid (BHA): salicylic acid, which is derived from willow or myrtle tree bark. Unlike AHAs, BHA is oil-soluble. This means BHA can penetrate through the oily sebum into skin's pores and exfoliate dead cells within the pore. Oil solubility makes BHA the preferred hydroxy acid for people with oily skin who have blackheads and whiteheads. In fact, salicylic acid is a common ingredient in acne treatments. BHAs are effective at lower concentrations than AHAs.
How Hydroxy Acids Work
Hydroxy acids function primarily as exfoliants. They penetrate the dead, damaged cells on the skin's surface and loosen the glue-like structures that bind this dead skin to the rest of the epidermis (topmost layer of skin). This allows the dead cells to slough off, revealing fresher skin cells. The result is smoother, more youthful-looking skin. Hydroxy acids also draw moisture to the newly exfoliated skin, and they may stimulate the production of collagen and elastin, which contribute to skin's tone and resilience.
Benefits of Hydroxy Acids
With daily use, hydroxy acids may reduce the appearance of wrinkles and improve roughness and mottled pigmentation caused by sun damage. Long-term use and higher concentrations allow hydroxy acids to penetrate to the dermis, the deeper layer of skin where wrinkles are formed. Salicylic acid and glycolic acid in particular may be helpful for acne-prone skin, reducing blackheads and pimples and smoothing scars.
Safety and Side Effects
Skin irritation and sun-sensitivity are the major side effects of hydroxy acids. People using skin care products that contain hydroxy acids may experience redness, itching, burning, pain and possibly scarring. Scarring and hyperpigmentation (darkening of skin) are most likely for people with darker skin. BHA causes less irritation than AHA, even though it penetrates into the pore, because it has anti-inflammatory properties.
The new skin revealed by hydroxy acid use is highly sun-sensitive, so it's critical to use high-SPF sunscreen if you're using a skin care product that contains these substances.
Member Comments