Sensitivity test – Overview
It is possible to be allergic to anything, be it natural or man-made like a food such as a nut, a medicine or a cosmetic product. Some hair dyes have stronger chemicals than others, but it is possible to have a reaction to even the most natural colours such as henna. So a patch/sensitivity test is a way to check that you are not allergic to that product.
Sometimes during cancer treatment the skin is particularly sensitive. You can carry out a patch/sensitivity test for almost any product. So if you are thinking of trying a new product and have any concerns follow this simple guide.
- Why carry out a sensitivity test before colouring hair?
- How to carry out a sensitivity/patch test for hair colour
- Perms and other chemical process
- Semi-permanent make-up
Why carry out a sensitivity test before colouring hair?
A patch/sensitivity test is the best way to try and check that you are not allergic to a product. Whilst this guide is centered towards testing against sensitivity to hair colourants you can use this guide to do a patch/sensitivity test for almost any product. When it comes to hair colour a professional salon will normally carry out a test for you. If you are using a home kit, the instructions on the pack will tell you if you need to do one and how to do it.
It is possible to be allergic to anything, be it natural or man-made, like a food such as a nut, a medicine or a cosmetic product. Some hair dyes have stronger chemicals than others, but it is possible to have a reaction to even the most natural colours such as henna.
Many people get the possible issue of an allergic reaction to hair dye confused with possible damage to hair that could be caused by colouring hair or indeed the issue of hair loss. These are separate issues. In other words, having an allergic reaction to ingredients in hair dye is nothing to do with the length or condition of your hair or to do with hair falling out due to a side effect of treatment. In other words, having an allergic reaction to ingredients in hair dye is nothing to do with the length or condition of your hair.
What ingredients can cause serious allergic reactions ?
Some people are prone to a skin reaction called contact dermatitis. This means their skin becomes inflamed (red, dry and irritated) when they come into contact with a particular substance. The substance may either be an irritant, directly damaging the skin, or an allergen, triggering an allergic reaction that affects the skin.
The ingredient that is most well known for causing concern about skin irritation, and in some cases a very serious allergic reaction called anaphylaxis known as ‘anaphylactic shock’, is an ingredient called paraphenylenediamine, known as PPD. PPD can be found in some hair colourant and eyebrow and lash tint.
The possibility of a serious allergic reaction can be easily avoided by carrying out a patch/sensitivity test forty-eight hours prior to using the hair colour or dye, alongside following the manufacturers guidance.
Whilst serious allergic reactions to PPD are rare, it is impossible without carrying out a patch/sensitivity test to know if you may be affected. The good news is that every year thousands of women successfully carry out a patch/sensitivity test prior to applying hair dye to their new hair growth and have no problems from an allergic reaction.
It is important to be aware of the risk and know the facts about possible allergic reactions to hair colour. This way you can easily take precautions to avoid both skin irritations and allergic reactions.
PPD is often found in permanent and some semi-permanent hair colours. Generally speaking and especially in the case of the majority of permanent hair dyes, the darker the colour the higher the level of PPD.
There are a number of hair colours available that don’t contain PPD, however, they usually do still require you to carry out a patch/sensitivity test prior to use to check for other allergic and skin sensitivity reactions.
The NHS website provide medical information about how to avoid an allergic reaction to PPD and what to do if you do experience a problem.
How to carry out a sensitivity/patch test for hair colour
If you are colouring your hair using a semi-permanent or permanent hair dye it is good practice to carry out a patch/sensitivity test to avoid any possible allergic reaction to ingredients in the hair dye.
A patch test is easy to do and can be carried out by you or your hairdresser or in the case of a procedure such as semi-permanent make-up, by a technician. . Most manufacturers recommend that the patch test is carried out twenty-four to forty-eight hours prior to colouring. If you are using a home colour follow the manufacturers instructions.
It is very simple to do and normally takes less than a minute to apply. You normally apply a small dab of product behind your ear or inner elbow. You then follow the recommended instructions from your hairdresser or the product pack, to know what to look out for and when to wash the product off.
As long as you don’t experience any problems you can then go ahead and colour your hair.
If you feel experience any type of skin irritation or allergic reaction you should seek medical advice. It is important that you don’t use the product and seek guidance from an allergy clinic.
Perms and other chemical process
If you are having a perm or other chemical process you may also like to carry out a sensitivity test. Look on the manufacturers guidelines for best practice.
You must have a sensitivity test 24 to 48 hours prior to semi-permanent make-up application. The technician/beauty therapist who will be doing the procedure normally carries this out.
Next planned review: February 2022