Why Does Your Skincare Suddenly Sting When It Never Did Before? You apply the same serum or moisturiser you've used for months.But suddenly...It stings.Your first thought might be:“Did this product suddenly become unsuitable for me?”Maybe — but not necessarily.Sometimes, the product hasn't changed. Your skin condition has. Why Can a Familiar Product Suddenly Sting? Your skin isn't in exactly the same condition every day. Changes in your routine, environment, hydration, or skin barrier may affect how your skin responds to products. Some common possibilities include: Over-exfoliation Dehydration Skin barrier disruption Using too many active ingredients Recent treatments Environmental changes Existing