Daily Mail journalists select and curate the products that feature on our site. If you make a purchase via links on this page we will earn commission - learn moreWalk down the skincare aisle at Boots, nip into Space NK, or peek into your most glowy friend’s bathroom cabinet, and you’ll find one ingredient category dominating the shelves: acids.As aesthetic doctor and skin expert Dr David Jack says, ‘Acids can deliver everything from smoother, less lined skin to clearer pores to a more radiant complexion. While exfoliating acids are often associated with oily and acne-prone younger skin, they are excellent for mature skin, too.’This is because as we age, we become less efficient at shedding dead skin cells and so they accumulate on the surface, causing dullness. Acids can break down the bonds between the lingering cells so they dissipate, leaving a more light-reflective surface and a softer, smoother texture. This uncluttered skin then allows the active ingredients in products to penetrate the dermis better and get to work.Traditionally, acids have been split into two groups: alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs). Both do a similar job, but AHAs are water soluble, meaning they can’t penetrate into your pores where sebum is produced, so work on the surface. They are particularly suited to drier or more mature skin types. Poly-hydroxy acids (PHAs) work in the same way as AHAs but are better tolerated by those with sensitive skin. BHAs, however, are oil soluble, which means they can penetrate pores and help break down any gunk inside. All work to exfoliate on a chemical level (so avoiding the microtears that physical scrubs can inflict).It’s also worth noting that despite its name, hyaluronic acid is not an exfoliant like those listed above; when used in skincare it works to hydrate and plump.More key things to know? Acids are best when used topically on clean, dry skin and allowed time to penetrate (i.e., not in a face wash, where the contact time is minimal). Once you’ve given yours a few minutes to work, follow with your favourite serum or skip straight to your moisturiser or SPF. Never use your acid alongside serums and creams with highly potent active ingredients, like retinol or vitamin C. Oh, and acid products will also increase your sensitivity to sunlight, so it’s imperative that you use an SPF.If you’re trying an acid for the first time and know you have sensitive or delicate skin, you may want to do a patch test on the crook of your elbow or on your neck behind your ear. Start with one application a week and see how you go.My top tip is to use your chosen acid at night, then apply a soothing (slightly heavier) night cream, so you wake up to smoother, softer, more radiant skin. You can then cleanse and use your favourite vitamin C product and SPF in the morning without worrying about any active-ingredient crossover.Finally, avoid the eye area. The delicate skin there may not tolerate acids so well.Here’s what to use for your skin type:For ageing skinThe Ordinary Glycolic Acid 7% Exfoliating Toner (£8 for 100ml, boots.com) is a bestselling, powerful but purse-friendly buy. Just soak a cotton pad in this AHA before sweeping it over skin. You’ll see the glow before you notice your fine lines easing, so consistency of use is key.For spotsMedicube Zero Pore Pad 2.0 (£24 for 70 pads, cultbeauty.co.uk) is a personal favourite for my 36-year-old skin (reader, being afflicted with both clogged pores and wrinkles seems unfair). The pre-soaked pads contain AHAs and BHAs for maximum effect on lines and decongestion. Plus, with added panthenol and allantoin, they hydrate and soothe so skin doesn’t feel tight and stripped.For dry skinMurad Replenishing Multi-Acid Peel (£82 for 100ml, murad.co.uk) is a dual-phase acid. It has both AHAs and BHAs, with an antioxidant-rich, hydrating oil base on top. Shake it to mix, then apply using a cotton pad. The extra boost of hydration makes this cocktail perfect for those with drier skin. Plus, it contains tranexamic acid – not an exfoliating acid, but one that blocks the skin from producing pigmentation, so it’s good for those with age spots or darker skin.For sensitive skinTakami Daily Skin Renewing Soft Peel (£35 for 30ml, spacenk.com) is a new serum that’s gentle enough for daily use, combining 30 per cent glycolic acid with mild fruit enzymes to avoid disrupting the skin barrier. Reassuringly, Dr Hiroshi Takami, the board-certified dermatologist behind the brand, has 26 years of expertise, having treated half a million patients.For bumpy limbsAmeliorate Transforming Body Cream (£29 for 200ml, boots.com) is from a brand known for its skin-smoothing range, but my favourite is this AHA cream. Full disclosure, it does smell Sudocrem-esque, but boy, does it work wonders on my chicken-skin arms (keratosis pilaris) and rough, overlooked legs. Use at night after a shower if you’d rather nobody gets a waft of nappy cream, but do not underestimate its power. Just avoid on freshly shaved legs. It will sting.For dull skinSkin Rocks The Strong Acid (£75 for 150ml, skinrocks.com) is from a skincare brand founded by beauty influencer Caroline Hirons, who is so invested in acids she created a whole range. In April she launched this toner as she wanted something more ‘hardcore’ than you usually find on the high street. Formulated for more experienced users, it combines AHAs, BHAs and PHAs for resurfacing heft, and niacinamide to help reduce redness. Only use if you have a history with chemical exfoliants.