For hair that hasn't seen water in a while, this Drunk Elephant T.L.C. Happi Scalp Scrub ($36) really tackles dirt, dead skin cells, and other buildup by using an alpha-hydroxy-acid blend more commonly found in skincare. Scalps are left incredibly clean and marula oil adds back in some necessary moisture (though the plant-based scrub isn't too harsh or overly drying anyway).