A1. All permanent hair colours including Bigen require a skin allergy test before each use. Body constitution and condition are changing every day. Allergic reaction occurs depending on the constitution of the day of use. Please make sure that you do a skin allergy test before each use, even if you have been colouring for years without any problems.
You should carry out the test following the instructions provided 48 hours before application to see if you are allergic to hair colour product or not, every time you colour your hair with permanent hair colour product. If you notice any signs of burning, swelling, redness or irritation on your skin, do not use the product.