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Hair straightening

What is hair straightening?

Using heat to straighten hair strands.

What does hair straightening do?

  • Head hair

    Straightens and lengthens slightly

How long does hair straightening last?

The effects last until the hair becomes wet, but will gradually wear off over time.

How do I stay safe?


A common cause of serious injuries to children is burns from home use of hair straighteners.

If you are in a home containing children pay particular care to keep children away until the straighteners have completely cooled, which may take several minutes. Accidental contact with hot hair straighteners can cause permanent disfigurement and require skin grafting 1.

To reduce the amount of damage to the hair caused by straightening, it is important to use straighteners on dry hair, and to use a heat-protection spray 2.

How do I straighten my hair?

Hair straighteners (also known as straightening irons) use a pair of plates which are heated up to approximately 200°C. The heat and tension from moving the plates through the hair breaks chemical bonds in the hair proteins, causing them to straighten 3.

To straighten your hair using hair straighteners:

  1. Make sure your hair is completely dry and free of tangles

    Applying straighteners to wet hair might damage it, and straightening it with tangles still in will reinforce the tangles.

  2. Heat up the straighteners

    Plug in the straighteners and make sure they are switched on. Heating may take several minutes. Some straighteners may have an indicator to let you know when they are at the right temperature.

  3. If you have it, apply a heat protection spray

    Using a heat protection spray will reduce the amount of damage the straighteners will do to your hair.

  4. Split your hair into sections

    Using hair clips or hair ties, separate your hair into sections. This will help you make sure you don’t miss any bits of hair. If you have thick hair, you may need to divide it into more sections.

  5. Straighten each section in strands

    Take a strand of hair about 2 to 5cm wide and about 1cm thick. Holding the hair taut, run the straighteners smoothly along the length of the hair. Repeat this until you have straightened all the hair in one section, and then move on to the next section.

  6. Apply hairspray

    Once you are done, apply hairspray if you have it, which will make the straightening last longer.

  7. Unplug the straighteners

    Place the straighteners somewhere away from anything flammable while they cool. Keep them out of reach of children.

As your hair straightening will be undone if your hair becomes wet, it may be useful to invest in a shower cap, which will keep your hair dry while you wash the rest of your body in the shower.

Are there other options?

An alternative to hair straightening using heat is permanent hair straightening using chemicals. This approach lasts around 12 weeks between applications, instead of needing to be reapplied after each wash.

How much will it cost?

Hair straighteners come in a large range of prices, from £10 to over £100.


  1. 1.
    Jones, N Wilson, Wong, P and Potokar, T (2008) “Electric hair straightener burns an epidemiological and thermodynamic study.” Burns, 34(4), pp. 521–524. Link
  2. 2.
    Christian, Paul, Winsey, Nigel, Whatmough, Marie and Cornwell, Paul A (2011) “The effects of water on heat-styling damage.” Journal of cosmetic science, 62(1), p. 15. Link
  3. 3.
    Bryant, Harold, Dixon, Felicia, Ellington, Angela and Porter, Crystal (2015) “Hair straightening,” in Draelos, Z. D. (ed.), Cosmetic Dermatology: Products and Procedures, John Wiley & Sons, pp. 262–269. Link

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