Glossary
Patch test
Trying a product on a small area first. Behind the ear or on the jaw — not the wrist.
A patch test is applying a new product to a small area before putting it on your whole face, to find out whether you react to it.
Most people do it in the wrong place. Wrist skin is thicker and behaves differently from facial skin, so a product that is fine on your wrist can still sting your face. Test behind the ear or along the jawline — skin that is closest to what you are actually treating.
How to do it properly: apply a small amount once a day for three days, and leave it alone between applications. Watch for redness, itching, small bumps or burning. A mild tingle in the first minute with an acid or vitamin C is normal; stinging that persists is not.
It is worth the three days if your skin reacts easily, if the product contains an active you have not used before, or if it is expensive enough that you want to know before committing.
It is not a guarantee. Some reactions build over weeks rather than days, which is why introducing one product at a time still matters even after a clear patch test.
This article is general information, not medical advice. Skincare products are not medicines. Speak to a dermatologist about persistent or worsening skin conditions.