Once you are comfortable with glycolic acid, the rest of the shelf makes more sense, because each acid has a different job.

Lactic Acid 10% + HA 2% is a serum made for uneven texture, and lactic acid is generally thought of as the softer cousin of glycolic. Mandelic Acid 10% + HA is another gentle exfoliating serum, and I would try it first if your skin sulks at stronger acids. Salicylic Acid 2% Solution is an exfoliating serum for blemish-prone skin. Azelaic Acid Suspension 10% is a cream for redness and blemish-prone skin, and it feels more like a moisturizer than an acid, so it is the one I would try on a sensitive week.

Then there are two formats that are easy to overlook. The Salicylic Acid 2% Masque is a clay and charcoal mask for blemish-prone skin, a short-contact ritual, and the Salicylic Acid 0.5% Body Serum takes the same idea to the chest, back and upper arms, where bumps and breakouts often gather.

My rule for all of them is one acid at a time. The temptation is to build a stack because every bottle looks so friendly. Pick a single evening for each, write it on a note in your phone, and treat the rest of the week as rest days. If you get stinging that lingers, peeling or a tight shiny look, stop and let skin recover.

An acid night only works if the mornings and the moisturizer are kind to your skin, so this last grid is really the important one.

Caudalie's Premier Cru Skin Barrier Rich Moisturizer, with bio-ceramides, is what I put on after an exfoliating evening. It is rich and refillable, and it is made to support the skin barrier. Then comes sunscreen, because exfoliated skin is more sensitive to sun and daily protection is not optional. Supergoop's Glowscreen SPF 40 has hyaluronic acid and niacinamide and has a glowy name and a glowy finish. Kiehl's Better Screen is a mineral UV serum at SPF 50. Ultra Violette's Supreme Screen is a facial sunscreen, moisturizer and primer in one at SPF 50. Tatcha's The Milky Sunscreen is SPF 50+ with encapsulated ectoin and vitamin E, and it is a milky formula. Eadem's Sunsuede is an SPF 50+ stick that doubles as a blurring primer, and it is the one I keep in my bag for reapplying.

What I would skip: skipping sunscreen because it is cloudy, and using a retinol or a second exfoliant on the same night as an acid. Also skip scrubbing with a gritty product the day after. Acids already do the sloughing. Apply sunscreen generously, and again if you are outdoors for hours.

Here is how I would run a week if I were starting from zero. One night, the glycolic toner. Two nights later, a hydrating serum and a rich moisturizer with no acid at all. A third evening, maybe a mandelic or lactic serum if the first one felt easy. Every morning, sunscreen.

That leaves two or three rest nights, and those are not wasted. They are how skin gets used to exfoliation. Introduce only one new product every couple of weeks, so that if something stings you know the culprit. Patch test behind the ear or along the jaw first. Persistent redness, burning or a rash is a reason to stop and talk to a doctor. Keep a note of which night you used what, because memory is unreliable at eleven at night and skin keeps the score. Acids can be a lovely part of a routine, and they work best when they are the quietest thing on the shelf. If you want to keep browsing, I also put together Pantene Shampoo, Explained.