A flat iron can make your hair smooth, sleek and shiny, but over time it can cause the outer layer of your hair to become damaged, making it difficult for your hair to retain the moisture that protects it from breakage and dullness. You can tell your hair has been damaged when it's dry and dull, resistant to styling, prone to frizz in humidity and has split ends and flyaways.
Ask your stylist for a trim to get rid of damaged ends -- they can spread damage upwards into the healthy parts of your hair.
Upgrade your flat iron if you've had it for more than five years, recommends Beverly Hills-based celebrity hair stylist Cristophe. By that point, it's likely that your flat iron's temperature gauge isn't functioning correctly. Replace it with a ceramic flat iron -- it will heat evenly to reduce damage.
Wash your hair with a moisturizing shampoo to help restore missing moisture. Look for one that contains ceramides, nutrients, antioxidants and UVA/UVB protectors.
Use a protein-based hair conditioner to help fill in cracks in your hair's cuticle and smooth flyaways.
Dry your hair completely before using a flat iron. Blot it thoroughly with a towel or let it air dry before using a blow dryer to finish the job. If your hair is wet when you use a flat iron, the heat from the iron can make the water in your hair boil, damaging your hair.
Apply a styling spray or serum that contains dimethicone to your hair before using a flat iron, recommends Cheri McMaster, senior scientist for Pantene. Dimethicone melts when it gets hot, creating a protective barrier around your hair shaft.
If your hair is damaged by heat styling, consider switching to a hairstyle that requires less heat styling to look its best. Ask your stylist about cuts that play up your hair's natural texture or that look good air-dried.
Continue to protect your hair after flat iron damage has been repaired, or the damage could reoccur.