At this stage, most of us have used a product or two that contains hydroxy acids. Glycolic, lactic, salicylic—we’ve heard of them. We know they work, but what exactly does each of them do? How are they different from one another? And, most important, which ones do what best? Let us break it down for you.
How Hydroxy Acids Work
Hydroxy acids “smooth, tighten, firm and brighten,” says Stanley Jacobs, M.D., a triple-board certified facial plastic surgeon in San Francisco. And while higher concentrations of these acids are used in professional treatments, “almost everyone can tolerate them in lower concentrations and over-the-counter formulations, and will notice significant improvements in their skin when used as directed,” Dr. Jacobs says.
But how exactly do these multitaskers-in-a-bottle work? “Hydroxy acids weaken the ‘cellular glue’ that makes dead skin cells stick together, encouraging exfoliation and revealing healthy, younger skin cells,” explains Haleh Bakshandeh, M.D., a board-certified dermatologist based in Beverly Hills. “Hydroxy acids at medium-to-higher concentrations can also function beyond the surface of the skin and work in the epidermal and dermal layers to deliver additional results, such as collagen and elastin remodeling, pigment lightening and melanin suppression (i.e., keeping brown spots at bay).”
The Hydroxy Acid Alphabet
Hydroxy acids fit into three categories: Alpha hydroxy acids (AHAs), beta hydroxy acids (BHA) and polyhydroxy acids (PHAs). All three groups of acids are derived from various natural sources, such as sugarcane, fruit and willow bark. They also work similarly, but each one produces slightly varied results. The main difference? BHA is lipid- or oil-soluble, which makes BHA more effective on oily skin.
Though there are various types of acids, glycolic, lactic, mandelic and salicylic acids have the most clinical research behind them and the most studies supporting their efficacy. That’s why they’re also the most commonly used acids in skin care products. Here’s what else you need to know about each of them: Read more