HOW TO TRY NEW PRODUCTS

To sample new creams without breaking into a rash, stick to testing one at a time. If the new product has ingredients that may cause irritation—such as retinol or alpha hydroxy acids—keep everything else simple: a basic cleanser, no exfoliation, no antioxidants, and a plain moisturizer.
When you test it, slather the new product on the side of your neck rather than on your face so that you can cover any reaction with your hair. If it passes the neck test for three days, it's ready for your face.