We probably don’t need to tell you that there are a lot of acids in the skincare world. And while some, like Hyaluronic Acid or Polyglutamic Acid, are pretty low risk, exfoliating acids have more of a reputation for their fast results – and, less positively, a potential for irritation. But as well as AHAs and BHAs, there is another exfoliating acid category you might have come across: PHAs. Lesser known? Perhaps. Less worth your time? Far from it.