“If you’re using a new product or not necessarily sticking to a routine, then that can precipitate an irritation on the face,” says Mona Gohara, MD, a dermatologist at Yale Medical School. What’s more, using a wide range of products can make it difficult to single out what is causing a negative reaction. To find out which product—and, more specifically, which ingredient—is responsible, Gohara says you have to become a skincare detective. “I tell my patients to start the process with a clean slate. Eliminate everything and then reintroduce products every 10-14 days, because that’s how long it takes for your skin to react.” To avoid causing another reaction on your face, Gohara recommends trying a patch test at home. Place the product on the inside of your lower arm and look there for any irritation, but keep in mind that you should also monitor this area for two weeks before using the product on your face. RELATED: Here’s Why You’re Addicted to Your Lip Balm If you’d rather skip all of the testing and just replace your beauty products, Gohara suggests experimenting with products that are as biologically similar to your skin as possible, like a pH-neutral cleanser and a moisturizer with hyaluronic-acid and ceramides. If you’re unsure which products fit the bill, Gohara recommends Dove cleansers (she’s a spokesperson) and SkinMedica’s HA5 Rejuvenating Hydrator. The latter is pricier, but thanks to natural hyaluronic acid, it may be worth the hefty price tag for those worried about irritating their skin.