Dandruff itself is not a fungus, although it is caused by the presence of a naturally occurring fungus, Malassesia globosa
Dandruff is caused as this fungus breaks down oils on your scalp called sebum. This process produces oleic acid – something which 1 in 2 people around the world are sensitive to.
If you’re sensitive to it, your scalp becomes irritated and increases the rate at which it renews skin cells in an attempt to get rid of whatever is irritating it. This causes skin cells to clump together, forming flakes that we associate with dandruff.
Anti-dandruff shampoos work to get rid of dandruff by preventing them from forming the irritants that cause dandruff.