Dandruff can be caused by various factors but mostly it is merely a build up of dead skin over time. Very often it could also be a build of product - maybe shampoo or conditioner not rinsed out properly. It my also be an irritation caused by using the wrong products or if you are shampooing too often. There are two things that help to fight dandruff: Firstly, you need to brush your hair more often with a brush that reaches your scalp. This will help to remove the dead skin that is causing the build up. Secondly, you need to use an anti-dandruff shampoo, but only while you are experiencing the problem. Anti-dandruff shampoo should be used as a cure for dandruff and not as prevention as it strips your hair from its colour.