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Flat iron or relaxing: which damages your hair more?

Monica questions: What causes more hair loss straightening you hair with a flat iron or doing a relaxer at a salon?

Left Brain straighteners her out:

Great question Monica. A quick answer is that Relaxers lead to more hair loss than Flat Irons. Read on for why. If you want some additional options to flat irons and relaxers take a look at this post we did on 7 ways to straighten hair.

How Hair Straightening Processes Work

While relaxers and flat irons can give you similar styles, they work in completely different ways. To understand how they work, you first must know that hair is made up of proteins. Within these proteins are chemical bonds responsible for hair strength & hair shape. The two most important types include Hydrogen bonds and Disulfide bonds. (There are others but Sarah’s eyes are starting to glaze over so I’ll stop there.)

Hydrogen bonds are weaker, temporary and dependent on the amount of water in your hair. When you flat iron your hair, you remove curls/frizz by first mechanically forcing hair straight and then removing the water with heat. It works just like an iron on clothes. This locks hair into whatever shape it currently is in. It works great as long as your hair stays dry. But once hair picks up moisture from the air, it will start to revert to its more natural shape.

Hair’s natural shape is controlled more by the Disulfide bonds. These permanent bonds don’t depend on how much water is in hair. With relaxers, hair’s disulfide bonds get broken down making your hair permanently straighter. At least permanent until new hair grows back.

Both relaxing and flat ironing damage hair but relaxing is much worse because it actually degrades hair proteins.

3 Kinds of Hair Loss

When you ask about hair loss you could be talking about 3 different kinds; breakage, natural, and permanent. Since I’m not sure which you’ve asked about, we’ll look at all three.

  1. Breakage: Everyone’s hair breaks to some extent, but damaged hair breaks more. Relaxing causes much more damage thus leading to more hair loss via breakage than flat irons.
  2. Natural: People shed just like dogs & cats. Your hair has a natural cycle where you lose about 100 hairs naturally each day. Neither relaxing or flat irons will affect this hair loss. You might notice more hair loss while flat ironing but that just because you pull out hairs that would have fallen out on their own.
  3. Permanent: In this type, hair stops growing at the roots & there is not much you can do to get it to come back. It’s unlikely that flat ironing will cause this but it is possible relaxing hair can. If your scalp is exposed to the chemicals in relaxers for too long, it can burn you and cause permanent hair loss. This isn’t a problem when relaxing is done by a top notch, professional stylist but if you have an amateur, look out!

For more, see this information from the FDA about hair relaxer safety.

Should You Relax?

Despite the safety concerns and extra damage, there are some significant advantages of relaxing over flat iron straightening. These include

  • More permanent
  • Easier to do (if you have a stylist)
  • More consistent results
  • Less prone to negative humidity effects

On the other had, being more permanent might be a negative to some.

The Beauty Brains Bottom line:

Both relaxing and flat ironing damage hair, but relaxing is much worse. However, it does give some added benefits so you might decide hair relaxing is worth extra damage. If you don’t want to lose or damage hair, the best thing you can do is shampoo infrequently, condition each time, and don’t comb or style it much. Of course, that severely limits the type of looks you can get so these aren’t options for most people.

What do YOU think? Would you rather have hair relaxed or do daily flat ironing? Leave a comment below.

Comments on this entry are closed.

  • Furry Lee September 30, 2015, 5:21 pm

    I prefer using a flat iron. When I wash my hair once per month it retains the natural oils and grows very fast. In the past I used a relaxer and the hairline particularly at the front is very damaged. I have bald spots that will never seem to grow hair again. What can I use on these bald spots to bring hair back to life?


  • Joan C. Quinn October 16, 2015, 2:03 pm

    prefer using a flat iron. When I wash my hair once per month it retains the natural oils and grows very fast. In the past I used a relaxer and the hairline particularly at the front is very damaged. I have bald spots that will never seem to grow hair again. What can I use on these bald spots to bring hair back to life?

  • Walter B. Havens November 10, 2015, 2:15 am

    I think if we make sure and understand clearly how to use and how many time use per day, we can protect and enjoy with Hair Straightener Products, but if you don’t find the way may be hamrful with your hair, so before use should understand about all product as you understand your hair.

  • waqas khan December 19, 2015, 9:27 am

    Flat iron is the best for hair
    After using this you definitely use hair spray and straightnig chemical products for some good texture.

  • Barbara. W January 8, 2016, 6:25 am

    Great sharing post. I always using the hair conditioner in order to reduce the bad effects of flat iron hair. Thanks

  • Linda February 25, 2016, 2:34 am

    When I was 14 I would get up at 4 am (that’s 4 hours before leaving the house!!!) to straighten my hair with a super cheap, super old hairstraightner, which is why it took me ages. I would not leave the house if my hair was not bone straight. Funnily enough now I want curly hair, which is why all I do is wash it and let it air dry if time/the weather allows it. I like the natural wavy beach hair look!

  • BNYC500 March 24, 2016, 7:59 pm

    Daily heat from the hot iron will strip your hair of moisture. This causes quite a bit of unnecessary damage – If heat is needed, aim to keep the temperature below 400 degrees. You also should use a Leave in Heat Protector before you hot iron. I use the Shielo Leave in Protector before I hot iron or blow dry. Plus it leaves my hair smelling great for two days. NO BURNT HAIR SMELL

  • Hair Care July 24, 2016, 8:35 pm

    Great read. Your tips and information are very helpful. True that relaxing gives less time but the chemical use can damage hair more. I preferred flat iron, there are leave in protector to use and besides you don’t have to straighten your hair everyday. Thank you for sharing.

  • Olydia August 26, 2016, 8:53 pm

    Did anyone know that heat damages hair and thins it out.I relax my hair all the time and my hair never damages because I use shampoos in high protein and it never breaks.You have to know the proper remedy to care for your hair when it’s relaxed and get a professional to do it.

  • Dee February 26, 2017, 1:15 pm

    I’ve had more split ends while flat ironing than relaxin. I prefer relaxing, as long as you moisturize, no split ends. If you keep flat ironing natural curls, eventually you’ll have no hair left!

  • FlatironVictim November 16, 2017, 3:04 pm

    Hello people,
    ive a problem: i used flat iron on my damp hair like 4-5 times. i didnt know that the hair has to be dry before flat ironing but anyways, its too late now, i already did it. the problem is, that even after shaving all of my hairs off, my hair dont seem to get as thick as it was before. its so thin and brittle now, the new growing hair too… im already waiting 7 months its so desperating. my scalp shows more now. im 18 years old and male and its no mpb!

  • Becky January 23, 2020, 3:40 pm

    I quit straightening my hair but now how do I get it healthy again and grow