Anti-dandruff shampoo with tea tree oil This shampoo combines tea tree oil and piroctone olamine to soothe itching and reduce dandruff. It helps prevent new flakes and calms dry, itchy scalps. The result is shiny hair and a healthy scalp. Dermatologically tested and approved. Instructions for use Use a walnut-sized amount, depending on hair length. Apply evenly to wet hair, lather, and gently massage into the scalp. Leave on briefly, then rinse thoroughly.