Incorporating urine into a skin-care routine isn’t some new hippy-dippy thing Gwyneth Paltrow is touting. It’s an ancient Eastern tradition, believed to heal external ailments using the body’s natural antibodies released in our urine, which is “sterile, antimicrobial, and has anti-inflammatory properties,” says dermatologist Joshua Zeichner, MD.

As expected, there are some caveats to washing or toning your face with urine, says dermatologist Whitney Bowe, MD. 1. You should only use your own sample (phew). 2. You must use it immediately to avoid bacteria contamination — no waffling! 3. Do not try this if you’re prone to UTIs, have diabetes, or take oral medications which can react with the skin in unexpected ways.