The secret to hair without visible dandruff: the Selenium S Active molecule Selenium S Active, a very powerful anti-dandruff agent, is designed to act effectively without attacking the scalp. It is distributed evenly and fixes itself to act: 1 Quickly From the 1st use, it attacks dandruff to eliminate even the most stubborn and quickly soothe the sensation of itching. 2 Long-lasting It is so effective that it continues to act for weeks, even if the treatment is interrupted.