Colouring hair is an age-old practise, but now even youngsters are taking to it. So, it is imperative to know its side-effects

Dr Vikas Sharma

Hair colouring is a procedure commonly used by both elderly people to conceal their grey hair and youngsters to achieve a trendy look. However, in some cases it can be associated with structural and systemic side-effects. Hence, one should be aware of the types and components of hair colour to prevent the same and reduce structural effects on hair.

Natural hair colour manifests itself in a vast multitude of shades and tones – from the lightest blonde and warmest brunette to the most vibrant red and deepest black. Hair dyes can partially remove natural hair colour, add new artificial colour, or indeed do both at the same time. Semi-permanent hair dyes use a combination of preformed dyes to obtain results that last up to six to eight shampoos. Semi-permanent and permanent hair dyes involve oxidative chemistry, requiring different product components to be mixed just before they are applied. Oxidative colouring and bleaching have been shown to cause several changes to the hair structure. Key hair dye actives such as para-phenylenediamine, but also para-toluenediamine are well-known skin sensitizers.

How does it effect?

It’s the result of a series of chemical reactions between the molecules in hair, pigments, as well as peroxide and diamines. The symptoms and damage may not show up immediately and may take days or even weeks after hair colouring sessions. Whether you are colouring your hair to hide the greys or just experimenting, you could be at risk of dermatitis. The primary perpetrator of dermatitis is a substance called para-phenylene-diamine or PPD. The most common symptom of allergy caused due to hair colour, include itchy scalp, redness and swelling in the scalp, swelling around the eyes and eyelids, and scaly skin.

Hair colouring involves the use of chemicals capable of removing, replacing and covering up pigments naturally found inside the hair shaft. Due to repeated colouring, your hair gets over-processed. The chemicals strip moisture from your hair making them dry and brittle. To overcome this, newer hair colours are coming up with composition enriched with antioxidants and hydrating molecules. Hair colours may also cause skin reactions and some common symptoms include redness and flaky skin, itching, burning sensation or more rarely, anaphylaxis, which is a life-threatening condition requiring immediate medical attention.

Testing is a must

A lot of people at home just buy a box, skip the test, and put it on. This is a mistake as the patch test is our first line of defence This should be done at least 48-72 hours before you plan on colouring your hair. To test, put a dab of colour behind your ear and don’t wash it off for two days. If you don’t have any signs of allergic reaction, such as itching, burning, or redness at the test spot even after 72 hours, you can be somewhat sure that you won’t have a reaction to the colour when it’s applied to your hair. If you do react to the patch test, do the same test with different brands or colours until you find one to which you’re not allergic.

Do not use colours containing lead acetate on any parts of the body other than the scalp. Medicated hair colours are now available, which can be prescribed by dermatologists in case one is sensitive to hair dyes.

(Dr Sharma is a Panchkula-based skin specialist)