Dandruff is caused by overstimulation of the scalp, irritating chemicals, and excess sebum produced by overly strong cleansing shampoos. That can overstimulate the growth of Malassezia, a fungus that takes over the scalp, causing itching and flaking skin. CALM anti-dandruff shampoo contains two specific ingredients known to address Malassezia and is formulated to be the mildest anti-dandruff shampoo on the market. Additionally, four plant oils—rosemary, lavender, thyme and peppermint—all have positive impact on dandruff and scalp health.