Dermatology Review

To understand why the scrub felt like it worked and the bumps came back, you need to know what a bump is made of. There are three layers. Layer one — the surface: what you feel The sandpaper texture, the tiny raised cap on each follicle, the pink or red-brown halo around it, and the dry, dull skin in between. This is where scrubs, gloves, dry brushes and grit work, and it is where most people start: they take the caps off, the arm feels smooth in the shower, and for two days it looks better. But the cap is the top of a plug, and the plug is still in the follicle. Within a week it has grown back, and the skin around it — rubbed, stripped and reddened — is drier and angrier than it was.

Layer two — the structure: what is in the follicle Below the cap, the mouth of the follicle is packed with keratin. The cells that line it have stuck together instead of shedding, the plug they form holds the hair inside, and the skin around the follicle has thickened and dried into a stratum corneum that is tightly bound to let go of itself.3,4 This is the layer products work on: lactic acid and ammonium lactate loosen the bonds between the cells so the plug releases;6,10,12 urea, at ten per cent and above, does the same and holds water in the skin around it;16,17,34 salicylic acid, because it dissolves in oil, can follow the sebum into the follicle mouth rather than sitting on top.20 In the one randomised trial that measured it, twelve weeks of a ten per cent lactic acid cream reduced the bumps by two-thirds.6

Layer three — the root cause: why it keeps coming back The follicle is not blocked by accident. In keratosis pilaris it over-produces keratin as a matter of programming — the tendency runs in families, it is commoner in people whose skin is short of the barrier protein filaggrin, and the sebaceous gland that should keep the follicle mouth lubricated is often shrunken or missing.3,4 A follicle built this way does two things. It refills the plug as fast as it is removed. And it inflames whenever it is disturbed, which is what the halo is: rub it, scrub it, shave over it, dry it out, and it reddens and re-plugs. A cosmetic cannot change the programming. It can stop provoking it — keep the follicle mouth dissolved open with a keratolytic that does not sting, keep the skin around it supple with the lipids it is short of, and leave the grit in the drawer. In the one comparative trial that used a plain barrier ointment as the control, the ointment alone improved the bumps almost as much as the prescription cream it was compared with.9

This review was carried out independently by a cosmetic scientist LLM. Neither Dermatology Review nor its cosmetic scientist model has any connection to, or has received any payment, product, hospitality or other benefit from, any manufacturer or brand owner named on this page.

Carried out by an independent cosmetic science LLM. We set it out in full, step-by-step, so that you can judge it and so you can see what kind of each figure on this page is published data analysed by independent advanced modelling software. Step 1 — The audit In 2026 a modeller analysed the published data for 118 body treatments on sale in the UK sold for rough, bumpy or “chicken” skin: lotions, creams, milks, serums and scrubs, from high-street pharmacies, supermarkets, department stores, the specialist online retailers and the brands’ own sites. Face-only products, pharmacy medicines and prescription keratolytics were excluded. For products it recorded the full ingredient list, including declared percentage, the price per 100 grams, the on-pack claims, and the presence of fragrance, physical abrasives, drying alcohols and known irritants. Where a brand declares no percentage, the position of the active in the ingredient list was used to estimate its dose. Step 2 — The shortlist Seven products went through to full modelling. The finalists were chosen to represent every formulation approach in the audit — urea-and-salicylic cream, ammonium lactate lotion at a declared dose, ammonium lactate lotion at an undeclared dose, ten per cent urea lotion, five per cent urea milk, leave-on salicylic acid, and acid-plus-pumice scrub — and every price point, from £4.88 to £14.29 per 100 grams. Step 3 — The evidence map For actives in the seven finalists it identified the published human clinical trials at or near the declared concentration — 34 peer-reviewed papers, listed in the appendix — and extracted the effect sizes: the percentage reduction in bump count, the change in roughness, redness and hydration, and the time to effect. Where a manufacturer has published its own clinical or consumer study, it is logged as a brand claim and reported on this page as a brand claim. Step 4 — The user record It read the verified reviews of the seven finalists on retailer and brand sites and coded each one for four things: the speed of first result, stinging or redness, dryness and flaking, and whether the reviewer was still using the product after two months. What this means for how you read the page Findings below are a projection built from published evidence, not a measurement. Where it writes “is projected to” or “the evidence points to”, that is precisely what it means.

Key Findings Finding 1 — Dissolve and rebuild, or it comes back A keratolytic on its own opens the follicle; it does not stop the skin around it drying back into the next plug. Rebuilding is not the finishing touch. It is half the job. Finding 2 Adults with these bumps have usually been trying for years, and the reviews show the pattern: the product that stings is stopped, the product that scrubs is stopped, and the product that is stopped has an effect of zero. The products that keep their users are the ones that are comfortable, unscented, and still visibly improving at week eight.21,31

This is what the published evidence says about each. Lactic acid and ammonium lactate — the keratolytic Lactic acid loosens the bonds that hold the keratin plug together, and — at a working dose — it does something the other acids do not: it raises the skin’s own ceramide production and improves the barrier while it exfoliates.12,13 In the one randomised trial of these bumps that counted them, ten per cent lactic acid cream cut the count by two-thirds over twelve weeks, with hydration up and the improvement holding a month after stopping.6 Twelve per cent ammonium lactate has been the dermatologist’s reference lotion for rough, scaling skin since the 1980s.14,15 “The number is the whole story with this molecule,” says the independent cosmetic scientist model. Urea - hydration Urea is one of the skin’s own moisturising factors and, at low doses, one of the best humectants there is;18,27 from about ten per cent it becomes keratolytic, loosening the thickened stratum corneum around the follicle, and at twenty and above it is used clinically to strip hard skin.16,17,34 Urea does not sting the way the acids can, which is why the ten per cent products are often the gentlest. Salicylic acid — the right molecule Salicylic acid is the only common exfoliant that dissolves in oil, which is why it can follow the sebum into the mouth of a follicle rather than sit on top of it;20 the keratosis pilaris trial used it at five per cent.6 The GB and EU regulation caps salicylic acid at half a per cent in a body lotion and two per cent in other leave-on products.30 Glycolic acid Glycolic acid is a genuine keratolytic in leave-on use,10,11,22 and a ten per cent acid at the right pH is the ceiling the safety bodies recommend for a consumer product.31 Ceramides, niacinamide and the emollients — the other half of the job The skin between the bumps is dry and barrier-deficient, and a keratolytic that leaves it that way is opening a follicle that will close again. Ceramides, cholesterol and phytosphingosine rebuild the lipid mortar between the cells;23,33 niacinamide raises the skin’s own ceramide output;24 shea butter, mineral oil and dimethicone slow the water leaving;25 glycerin and the natural moisturising factors hold it in.26,27 Beyond cosmetics For bumps that do not respond to any of this, dermatologists use prescription keratolytics and retinoids, and laser treatment has randomised-trial evidence for the redness in particular.7,32 None of that is on this shelf, and none of it is cosmetic. A GP or dermatologist is the right next step if the products below have changed nothing. Mechanism claims are efficacy claims: each paragraph is limited to what the cited paper shows at the cited dose, and brand-published data are attributed to the brand. Keratosis pilaris is named descriptively throughout, as is normal practice in the category; the verbs stay cosmetic — smooth, soften, visibly reduce — never “treat”. Sample survey trade names belong to their owners and are used for identification.

If you have read this far, you have probably been scrubbing at this for years, and you have probably been told, in one way or another, that the problem is you. The problem is products built for the bump you can feel rather than the follicle underneath it. You now know the three layers, you know what a working dose looks like. That is more than most people have when they stand in the aisle. Use it. Whatever you choose, put the scrub down, give the tub eight weeks, wear sunscreen on your arms, and keep going.