How to Patch Test Skincare, and Why It Is Worth the Two Days
Applying a new product to a small, out of the way patch of skin for a day or two before using it on your face, to see whether your skin objects.
On the label
Many labels ask for it. Inside the forearm or behind the ear are the usual spots.
What it does not mean
It does not mean a product is risky. It means the maker cannot know your skin, and neither can a review.