La Roche-Posay takes its name from the French town whose thermal spring water sits at the centre of every formula. That water is naturally rich in selenium, and it is the reason the range has been built around sensitive and reactive skin for decades rather than as an afterthought.
The formulas are developed with dermatologists and tested on skin that reacts easily, including skin prone to allergy. Fragrance, alcohol and other common irritants are left out wherever the formula allows, and the ingredient lists are kept deliberately short.
The range is organised by concern rather than by product type, so Effaclar handles blemish-prone skin, Cicaplast dry and compromised skin, Toleriane sensitivity, Anthelios sun protection and Lipikar the body.