If your serum burns, gently rinse it off with lukewarm water and stop using it for now. Burning is not a reliable sign that an active ingredient is working especially well. Even an expensive or highly praised product may not suit your skin, so you don’t have to finish it.

For now, leave out other active serums and exfoliants and keep your routine simple. A cool, damp compress can feel soothing; don’t rub the area. If even a cream you used to tolerate starts to burn, don’t try new products one after another. If the burning is severe or doesn’t go away, or you notice significant swelling or blisters, have the reaction checked by a doctor.

Keep the packaging with the ingredient list and write down what else you applied beforehand. This can help narrow down the cause. A reaction alone can’t tell you whether a single ingredient, the combination or something else is behind it.