The science of normal hair prone to dandruffdandruff can occur when the skin on the scalp loses its balance. To effectively combat dandruff, you need to act on visible flakes whilst caring for the scalp, helping to maintain a natural balance.the secret to reducing the appearance of persistant visible flakesthe l'oréal laboratories have succeeded in developing a formula which harnesses the power of active selenium s*, an effective weapon against dandruff. Its formula covers the scalp evenly and acts:1 very fastacts from the first wash to reduce the appearance of even persistent visible flakes and maintain the scalp in optimal condition.2 long lastingso effective, see visible results for up to 4 weeks** even if you stop using it.proven clinical resultswith regular use, visible flakes appear reduced for up to 4 weeks**.*contains selenium disulfide, avoid contact with the eyes and broken skin.**after 4 weeks of regular use.