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What is a hair dye patch test? 4-step tutorial to do it with ease 

Hair dye patch tests are a non-negotiable when you colour your hair at home. Here’s how to do one in four easy steps to detect allergies to your dye before you colour. 

What is a hair dye patch test? 4-step tutorial to do it with ease 

Is it necessary to do a *hair dye patch test* every time you decide to change your hair colour? Yes, yes and yes again. It's easy to shrug it off if you're reinventing yourself as a redhead (for the umpteenth time), but this is one step in the colouring process not to skip, ever. Even if you've been colouring your hair for ages, it's still always possible to have an allergic reaction to hair dye – even if you've used that exact same hair dye before. Allergic reactions are rare, but they can be severe – the patch test helps indicate potential reactions ahead of time. Luckily, it's super quick and easy to do. Here are our *hair dye patch test instructions*: 


Apply a small amount of dye to skin

Wait 48 hours

Check for reactions. If there are none, proceed to colour

Go on to colour your hair if test is negative


Tip 1) To patch test your hair dye, apply it behind your ear first… 

If you’re wearing earrings, remove them before getting started. Pour a little bit of your mixed colourant onto a cotton bud. Using the bud, dab a small amount onto the back of your ear, to an area of skin around the size of a small coin (1-2 cm² is fine). Allow it to dry completely. Then, reapply in the exact same way, two or three more times, making sure you let it dry between each application. You can then reseal your colour carefully and keep it for your actual colour application – in 48 hours. Don't worry: it'll still be good to use then.  


Tip 2) To check for an allergic reaction, leave it on for 48 hours…

So how long do you need to leave this *hair dye allergy test* on your skin? It takes two days to get the results of your hair dye patch test. Why 48 hours? In order to detect a potential allergy to the hair dye, you need to give your immune system time to respond. Most allergic reactions will occur within 48 hours of skin exposure, hence the 48-hour window for the *hair dye patch test*. 24 hours won't be enough time to rule out a reaction, so be sure to leave it on for the full allotted time. While you're doing the test, be careful not to wash, cover or touch the area.  


Tip 3) To rule out an allergic reaction, look for these signs…

Once the 48 hours is up, your *hair dye patch test reaction* results are ready. If you notice any itching, redness or swelling on the area where you've applied it, then you've experienced an abnormal reaction. If that happens, do not apply the product to your hair.  


Tip 4) Go on to colour your hair…

If you haven't noticed anything strange in the skin test area, then you can colour your hair. Go back to your bottle of dye, mix it up and apply it according to the instructions, then switch the focus to getting your colour perfect. Remember: if you experience any of the reactions mentioned in tip 3 above during the colouring process, you should rinse it out immediately. Top tip: you'll get the most intense, vibrant colour with an oil-powered dye like Olia. Or, if your strands are in need of repair, go for the nourishing Garnier Color Naturals. Enjoy your fresh, new colour! Just don't forget to pencil in a few minutes for a patch test before you get your next touch up.