Due to the oily texture of the Topical Oil (black bottle), you will want to wash it out. The oils will not clog your pores as they saturate your roots. If you shampoo every day, choosing a sulphate-free shampoo will be better for your hair. If you do not shampoo every day and want to benefit from the Topical Oil, you may prefer to apply the Oil to your scalp on the night before you shampoo and leave it on overnight. You can use the Topical Serum during the day.