The LASH, BROW, HAIR and SKIN products should not cause discomfort or irritation. If you tend to have a sensitivity to products, we recommend a patch test prior to use. This usually involves dabbing a small amount of product behind your ear or on your inner elbow and leaving it to dry for 48 hours.  Individual sensitivities to cosmetic ingredients are a fact of life. According to the “Allergic Living” database, it is a common myth that allergic reactions automatically become worse with each exposure. However, the severity of future reactions is unpredictable. It could be the same, less, or more severe. It is important to talk to your doctor about how to avoid allergens.