The thinner the skin, the gentler you have to treat it. And next to the delicate eye area, the lips are the thinnest skin on your entire face. That said, even if your face can handle potent active ingredients (retinoids, AHAs or BHAs, and the like), the skin around your lips may need some buffer.
OK, so you don't apply these ingredients to your lips during your routine (unless you choose to do a lip scrub, for example) but Landriscina says it's pretty easy for most products to apply to your lips for most products, especially cleansers . "
If you use an acidic laundry detergent in your skin care regimen, these ingredients can easily splatter your lips when you rub it in. Tapping in serums or overnight treatments will make it a little easier to avoid the area, but these ingredients can still find their way to your lips – and thus an irritated pout.