What Is The Patch Test?
The patch test is a way of determining an individual’s sensitivity to products, including cosmetics. To make the test, a small area of the skin behind the ear or upon the inner surface of the forearm is cleansed, then a small quantity of the cosmetics as prepared for use is applied to the area and allowed to dry. After 24 hours, the area is washed gently with soap and water. If there is any redness, burning, itching, blistering or eruptions, the reaction is positive and the cosmetic should not be used. The patch test should be performed whenever permanent or semi-permanent hair dyes are used. Sensitivity to these ingredients may not reveal itself until after these products have been used a number of times and therefore the patch test should be repeated before each application. Other types of hair dyes are sold in Canada and these do not require routine use of the patch test because they do not cause skin irritations in most persons.
