What effects does it have?

What is it?

Using chemicals to lighten, darken, or change the colour of hair.

It's also known as Dyeing, Bleaching, or Colouring.

How long does it last?

The effects last hours to years depending on what chemicals are used.

More information

Warning

The chemicals involved in hair colouring may cause an allergic reaction. This is true even for “natural” hair colours such as henna 1. It is important to always perform a patch test first by using the chemicals on a small area 48 hours before applying it to the rest of your hair. This is especially important if you have ever had a black henna tattoo, as you may be at risk of death.

Hair colouring can either be done at home or by a professional in a hair salon. Colouring in a hair salon has the advantage that a stylist can help you select a colour that will suit you well, ensure that the chemicals involved are used safely, and can advise you how to take care of your hair after it has been coloured. Colouring at home is much cheaper but carries the risks of accidentally staining your face, ears, hands, or your towels and carpet.

Hair colour uses a lightening step called “developer” (usually hydrogen peroxide based), followed by one of a variety of dyes. Depending on the type of dye (in particular, the molecular weight), the dye penetrates the hair differing amounts. Dye that penetrates further will result in a longer lasting effect - from lasting a few washes to until the hair grows out.

An alternative to normal hair colour is to use henna. Henna is a natural hair dry extracted from a plant called “lawsonia inermis”. It comes as a powder that you mix with water to form a paste, and can be used to stain hair to make it look more red. Henna has the advantage that it is less harsh on hair than many chemical dyes, but the resulting colour can be unpredictable, and it is normally suitable only for brown or black hair 2. Some henna products blend henna with other natural colours to produce a wider range of colours. You can find some advice about using henna products on the website of the cosmetics retailer LUSH.

Costs

The typical cost is around £1-10 for home colour and £25-75 for salon colour.

If you decide to maintain the colour, you will need to regularly revisit the salon every few months to add colour to the new hair that has grown from your scalp. This will normally be cheaper than the original appointment for colouring.

You can buy henna for £5-10 from Holland and Barrett, Lush, and some branches of large supermarkets.

References

  1. 1 Groot, Anton C de (2013) “Side-effects of henna and semi-permanent black henna tattoos: a full review.” Contact dermatitis, 69(1), pp. 1–25.
  2. 2 Peacock, Libby (2005) Good Hair, New Holland Publishers, London.

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Page last updated: September 2017