Got lackluster locks? These products get to the root of the problem. Pantene Age Defy Advanced Thickening Treatment ($19; drugstores) fills follicles with vitamins and caf-feine, fattening present—and future—strands. A protein blend in Peter Thomas Roth Hair to Die for Hair Treatment ($58; sephora.com) boosts newrowth and prevents hair loss. And Redken’s Intra Force line ($15 to $45; redken.com for salons) treats the scalp with an amino acid said to maximize hair health.