Before using Jolen, always make a preliminary patch test to see if you are or have become allergic/sensitive to the product. To do this, simply mix a small amount of the product as described on the box and apply to about a one inch square area of your inner arm. After 10 minutes, wash the mixture off with cold water and wait 24 hours. If redness, irritation or eruption appears, do not use the product. If necessary, speak with your healthcare provider.