How to do a Patch Test
A patch test is a simple, straightforward method used to determine whether a product causes an allergic reaction to the skin of the person being tested.
Wash, clean, and dry the area on the upper arm near the crook of your elbow. Apply a small amount of product to be tested and cover with a bandage. Leave the bandage on for 24 hours, then remove and check for irritation.
If skin looks clear and there is no reaction after the allotted test time, the product is presumably safe to use.
If you feel irritation at any time during the test, remove bandage and wash area with soap and water. Check with a healthcare professional whether it is advisable to use the product.