Shampoo is always good for the hair as it cleans the pores from the hair and makes it smooth and silky. But overuse of shampoo may at times destroy the roots of hair and cause unprecidented and permanent damage to our hair. Also using shampoos which are herbal can really help our hair in the long term,instead of using chemical shampoos.
I think you should better choose aurvedic or herbal shampoo. It may cause less harm to your hairs. If possible, use mehendi. It is good for hairs and skin.
Isha even my hair is also brown. it will look as if I colored.but i use sunsilk. the day I wash with sunsilk that day my hair look black after that day it comes to its original color