Truly sensitive skin has a very low tolerance for fragrance and preservatives, as well as anti-aging ingredients such as retinol, AHAs, vitamin C, and many botanicals. If this sounds like you, test any new product on a small section of your neck, then observe it for 3 to 4 days to see if a reaction occurs. As a general guideline, dermatologists advise sensitive-skin patients to stick to products with fewer than 12 ingredients and zero fragrance.

In my opinion, whether you have sensitive skin or not, it is best to assume that you have it, and stick to non-irritating ingredients in any skincare products which you use (or wish to try out). This way, you can avoid any potential mishaps on the skin.