PHAs (Polyhydroxy Acids) are part of the hydroxy acid family along with AHAs (Alpha Hydroxy Acids) and BHAs (Beta Hydroxy Acids). Considered as the new generation of AHAs, they are renowned for their keratolytic effects, meaning they remove dead cells (desquamation process), which increases cell renewal and restores radiance to the skin. How do they act on acne marks?