Kwick - I have lifted this from the Caroline Hirons Website - its the most comprehensive website for reviews that I have found:
What’s in it?
Water (Aqua), Gluconolactone, Lactic Acid, Glycerin, Propylene Glycol, Niacinamide, Citric Acid, Ethoxydiglycol, Magnesium Chloride, Malic Acid, Vinegar (Acetum), Phytic Acid, Salicylic Acid, Cochlearia Armoracia (Horseradish) Root Extract, Arctium Lappa Root (Burdock Root) Extract, Rumex Acetosa Leaf Extract, Myrtus Communis Extract, Commiphora Myrrha Resin Extract, Allium Cepa (Onion) Bulb Extract, Thymus Vulgaris (Thyme) Flower/Leaf Oil, Sulfur, Sorbitol, Phenoxyethanol, Sodium Benzoate, Potassium Sorbet
What’s good about it?
Oh where to start? This was my first ever experience of an exfoliating acid, in Paris, 14 years ago. It was used at the beginning of a facial at Biologique Recherché and was immediately effective. It still sets the bar for me, exfoliating acid-wise. The now infamous ‘1970 Formula’ is only available in the US, as the EU has banned phenol since I first started using it. How rude of them.
In fairness, this formula works better than the 1970 formula, it has less of a ‘burn’ and doesn’t cause the skin to turn as red. Obviously, if you are a sensitive skinned user, that is preferable anyway..
This formula has gluconolactone, a poly-hydroxy acid, which is more gentle than glycolic, that also acts as an anti-inflammatory along with a higher concentration of lactic acid – and malic and phytic acids, both AHA’s used to promote cell turnover and help with hyper pigmentation.
The acids in this tackle skin problems from every angle – resurfacing, zapping blemishes, essentially ‘stripping back’ the skin so that what you use after it is more able to penetrate. I try and use P50 in the evenings when I’m following it with retinols/vitamin A serums or pigmentation products. That’s why I generally use the others during the daytimes. Not a solid rule, more when I remember…