When it comes to damaged hair, it's best to use a flat iron that has adjustable temperature settings and ceramic plates. This will help prevent further damage to your hair. Some of the best flat irons for damaged hair include the BaBylissPRO Nano Titanium-Plated Ultra-Thin Straightening Iron, the CHI Original 1-Inch Ceramic Flat Iron, and the HSI Professional Glider Ceramic Tourmaline Ionic Flat Iron.