I've been contemplating using a hair iron often since it is so quick and easy to use in the mornings.

How bad is it or the hair's health ?

Here is what to do to prevent hair damage when using a hair iron: Run the iron quickly over the section of hair... leaving it on one spot for too long can cause damage. Use a heat protecting spray as well. Many brands make them and it will protect your hair.

As long as you are careful, your hair will be fine! If you have hair that's already damaged or fragile, it may not be a good idea. Keep in mind that color treated hair needs a little extra care too. Be sure to deep condition every now and then. You may also want to stick with flat ironing your hair only a few times a week instead of every day, BUT I do have a friend who blow dries AND irons her hair every day and her hair looks great. She just gets her hair trimmed regularly to prevent any split ends.

So, a flat iron won't damage your hair when used carefully, but many people OVER use them or let it sit on one spot for too long and that can cause breakage and split ends.

I agree with tUrRrRa. The key is to use a very good heat protectant spray, gel, lotion. I blow dry my hair and use a flat iron every day during the week and once on the weekends. Do get lazy on Saturdays. Been doing this for about 1 1/2 years now. With regular trims as mentioned, you should be fine.

I personally like "Rusk Thermal Str8" spray. It makes your hair pin straight without having to go over the area so many times with the flat iron(which is a good thing!). Its alittle expensive, but it goes along way, and is worth the money($14.00 cdn).