$tackz said:
it's most likely just to clean dirt from the hair so the ingredients can reach the scalp more efficiently.
i'd say use a regular shampoo for the first application, and revita for the second. that's what i do with nizoral... no need to waste it.
In a very polite manner, I would like to point out a flaw in your thinking.
nizoral is supposed to work on the scalp and not on the hair strands. In a way, nizoral is not your normal everyday shampoo. So, cleaning the hair so that nizoral can work on the hair is pointless, also many people point out that nizoral actually dries the hair.
nizoral is a potent medicinal shampoo, and leaving it on for 5 mins should be more than enough.