Patch tests are an easy way to help predict if you will have a negative initial reaction to a new product. It is recommended to perform a patch test before incorporating a new product into your routine. ​ Leave-On and Rinse-Off Products: Apply a small amount of the product on to a clean area of skin on the upper forearm. Keep the area dry. After 24 hours rinse the area. If any redness, burning, itching, blistering or irritation is observed at any time throughout the test, do not use the product. ​ Face Masks: Apply a small amount of the product onto a clean area of skin on the upper forearm. Leave-on for the specified length of time stated in the directions of use of the product. Rinse off when the specified time has passed. If any redness, burning, itching, blistering or irritation is observed within 24 hours of the patch test, do not use the product. Please note that the patch test is only for determining initial irritation reactions to products and does not guarantee similar results when applied to other areas of the body (including the face) or after continuous use. It does not account for underlying conditions and should not be used for the diagnosis of hypersensitivity or allergic contact dermatitis. If you are concerned about starting a new product, please consult a dermatologist prior to use.