For brunettes with highlights, blue shampoo should be a non-negotiable for keeping your color fresh and brass-free for months. Purple shampoo is a blonde’s best friend. The violet formulas work to ...

Pro tip: If you’re hesitant to go for a full-blue moment, match your shade of blue to your skin’s undertone, says Hernandez. “Cool and neutral skin tones can wear most cool-toned blue hair colors, ...