Sensitive skin

For dry, sensitive skin, the Aestura Atobarrier 365 Cream uses high-density ceramide capsules to keep skin moisturized for five days. The Etude House SoonJung 2x Barrier Intensive Cream is fragrance free, with panthenol and madecassoside to comfort stressed skin. If redness is the issue, the Dr.Jart+ Cicapair Intensive Soothing Repair Cream helps calm the look of redness and strengthens the barrier, and for sensitive, breakout-prone skin the Dr.Althea 345 Relief Cream soothes and hydrates without stickiness.

Behind the ear or on the inner forearm, the same amount you would use on your face, for three nights running before it goes near your cheeks. One new product at a time, with about a week between additions, so you know what caused what. If skin stings, flushes or comes up in small bumps, stop and go back to the routine that was working.

It means introducing them slowly and one at a time. Niacinamide and PHA are the usual first choices for reactive skin because they tend to sit well alongside everything else. Acids and retinal come later, at the lowest strength you can find, on a couple of evenings a week, under a rich moisturizer. Skip them in a week when your face is already unhappy.

Often, though not always. Added fragrance and essential oils are what most people find they react to, so dropping them is the first thing to try. Alcohol high in a list, strong acids and a cleanser that leaves skin squeaky are the other usual suspects. If almost everything stings, cut back to cleanser, moisturizer and sunscreen for two weeks, then add steps back slowly.