Choosing between keratin and protein treatments depends on what your hair is missing. Keratin smooths, softens, and reduces frizz—perfect for hair that’s dry, puffy, or hard to manage. Protein treatments, on the other hand, rebuild and strengthen damaged strands, especially if your hair feels weak, brittle, or over-processed. Understanding the difference helps you pick the treatment that restores your hair’s health, shine, and strength the right way.