Scratching your scalp can be damaging if you scratch to hard. Your scalp is skin and scratching it removes skin cells. Scratch to hard and you remove to much skin, the same skin your hair is trying to grow out of. This hurts the scalp and the productiveness of hair growth. Your hair follicle is at risk when scratching to hard which can result in unwanted hair loss, breakage, etc. Make sure to Rub your scalp with your finger tips and not dig with your finger nails. The digging will definitely remove more skin cells than need be causing unnecessary dryness and your scalp will need to repair itself which will prolong your growth.