The question "can you use purple shampoo on brown hair" pertains to hair care and color correction. Purple shampoo is designed to counteract brassiness in blonde hair. It does this by depositing purple pigments, which neutralize unwanted yellow tones.
Using purple shampoo on brown hair is not recommended as the pigments will not have any noticeable effect. Purple shampoo is specifically formulated for blonde hair and is not suitable for other hair colors.