The invention provides a method for improving hair biology, e.g., hair growth. The method comprises administering to a subject a monoamine oxidase inhibitor and a vasodilator, a zinc salt of a carboxylic acid, a xanthine compound, pyrithione or a salt thereof, saponin, tritapene, crataegolic acid, celastrol, asiatic acid, an inhibitor of 5-alpha-reductase, 1,4-methyl-4-azasteroid, an androgen receptor antagonist, azelaic acid or a derivate thereof, cyclosporin, triiodothyronine, diazoxide, retinoic acid, a prostaglandin analogue, aminexil, carnitine tartrate, apigenin, procapil, or adenosine, in an amount effective to achieve a desired effect. The invention further provides a method of reducing or delaying the appearance of an age-related skin imperfection. The method comprises administering to the subject a composition comprising an MAO inhibitor. A kit for improving hair growth also is provided.
