You can in fact neutralize your hair with ACV but i always like to use neutralizer after. It is wonderful though, most times after I use ACV, I hardly, if ever, see any pink suds, it speeds up the neutralizing process dramatically. So to me, regular neutralizing shampoo is more of a safety guard, its not neccessary, just as long as something is bringing down the Ph levels, like the profectiv relaxer that uses a neutralizing mousse instead. Shampoo isn't always the best route, I remember one relaxer I neutralized many times with shampoo and a week later, I happened to wash w/ neutralizing shampoo and I still had pink suds even though they appeared to be over with before. After using acv, I never experience that, so I would never neutralize without it.