Hear that? That’s the sound of a thousand fairies slowly perishing, which happens to make the exact same noise as your hair frying between two 400-degree metal plates. “Without proper protection, high heat irons will just burn and break your hair off,” says Streicher.
Certainly, different hair types can handle varying levels of heat. For fine hair, straightening and curling should be kept to lower temperatures (like 300 degrees tops). Coarser-textured hair can handle a bit more heat. “When in doubt, bring your flat iron or curling iron to your next appointment and ask your stylist,” says Cranford.
And always, always use a heat protectant. “That poor hair—it needs a product to help it fight off the negative effects of heat at that moment,” says Rez. “Not using heat protection when using hot tools will take a major toll.” Try Redken’s Iron Shape 11 Heat Protectant Spray, $20.
Also, most importantly, minimize the number of days a week you’re flat ironing and curling your hair. (Our experts actually couldn’t agree on whether everyday heat styling or the last point on this list was *the worst* for your hair). Streicher, for example, says, “Overusing heat on your hair consistently is the biggest way to damage your hair.”