Here's how and why you need to patch test for allergies before you colour your hair

You've found your perfect hair colour match and you're keen to dive right in. We know the feeling, but before you apply your colour there is one important step to complete, an Allergy Alert Test,  also commonly referred to as a patch test. While it's not always a big deal if you skip the instructions with some purchases, when it comes to hair dye, they're a must read. We guarantee whatever the brand of permanent colour, you'll be required to carry out a patch test 48 hours before using the product. While allergic reactions to hair dye are rare, it can happen, so an Allergy Alert Test is the best way to know if it's safe for you to use the product.
As it's the most important first step in colouring hair at home, we asked our expert team to explain why it's necessaryand how best to carry out an Allergy Alert Test. Here, Atelier colourist, Issie Churcher, walks us through how to do it  easily and safely yourself at home.

How the colour process works

"Permanent hair dye, whether it's for use in the salon or at home, requires a chemical to enable the colour process and the depositing of colour pigments in the hair," reveals leading colourist Josh Wood. The chemical used can vary, and like our Permanent Colour Kits it is often formulated with ingredients that are kind to hair and limit any hair damage caused during the colouring process. 

One of these commonly used chemicals you may have heard of is PPD  (listed in ingredients as Paraphenylenediamine). While our Permanent Colour Kits and Shade Shots (that are applied with the permanent colour) do not contain PPD, they do contain an ingredient called toluene-2,5-diamine sulphate, also known as PTD.

This has a similar chemical structure to PPD and works in a similar way to PPD to activate the colouring pigments for permanent hair colour.  People can still experience a reaction to this ingredient and that is why we stress the importance of carrying out an Allergy Alert Test for 48 hours before using the product, every time you colour your hair.
It's important that if you notice any abnormal reactions during the 48 hour window of the test, such as itching, redness or swelling in or around the test area, you should not apply the product. Please do get in touch if you have suffered a reaction to your patch test, we are happy to offer a refund as you cannot use the product.


How to patch test at home?

    • It's important to perform an Allergy Alert Test each time you colour your hair, even if you’ve used at home hair dye before and had no reaction, as skin can develop an allergy over time.
    • An allergic reaction can consist of itchy skin, redness or even blisters on your scalp, so it’s really important to do a patch test to avoid these. DO NOT use the product if you experience any reaction. 


    • Mix a coin-sized amount of the colour formula (A) and activator (B), plus the same sized amount of the Shade Shot Plus (if adding for a personalised finish) and mix together in a bowl.
    • Tip: It’s very important to fasten the caps on the bottles tightly after you have opened them for the Allergy Alert Test, to prevent the products oxidising and ensure the active ingredients will work after the test. Once products are mixed, they cannot be kept and should be disposed of carefully.
    • Use a cotton bud to apply a small amount behind your ear. Or use a cotton wool pad wrapped around the pointed tip of the colour brush in our Accessories Kit
    • Leave it on for 48 hours before washing off. You shouldn’t even notice it’s there, there may be a tiny dot of product residue visible but no marks or redness if your test is normal. 
    • If you have any signs of reaction, wash it off immediately and do not use the permanent colour. Please do contact us if this is the case and we will happily refund you for the product as you cannot use it.
    • If you show no signs of reaction to the dye, it is your all clear to go ahead and use your perfect shade match as instructed.
    • If you have any further questions on Allergy Alert Tests please do get in touch on or in the comments below. 

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1 comment

  • Hi I have the 6.5 to use on the roots of my balyage. I was excited about the ice blonde shade shot but now realising I can’t mix it as only doing roots. Can the shade shot be used as a separate all over toner to clean up my blonde ends?


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