a. Step away from the dandruff shampoo – I don’t care what wonders it promises your itchy scalp. Many mainstream dandruff shampoos are full of toxic ingredients like coal tar, selenium disulphide and zinc pyrithione – all synthetic ingredients that are harsh on aquatic species and ecosystems. Fight the flakes by washing your hair with natural tea tree oil shampoos instead or add a few drops of tea tree oil to your regular shampoo.