Tea tree oil: The other truly remarkable essential oil is the tea tree oil. It is anti-fungal and anti-bacterial in nature, enabling it to exterminate bacterial and yeast formation on the infection prone scalps. Tea tree oil is absorbed well by the scalp and can hence be left overnight to fight dandruff. It is very light on the scalp unlike other oils. However, it is advisable to apply the oil in combination with other oils like jojoba or olive oil in order to reduce its concentration, to avoid itching and irritation on sensitive scalps.