Ingredient Beauty BenefitsKeratosis pilaris
The rough little bumps on upper arms and thighs.
Keratosis pilaris happens when keratin builds up at the opening of a follicle and plugs it. It favours the outer upper arms, thighs and buttocks, and feels like sandpaper.
It sits across both pores and texture, which is why it has its own page. The ingredients used overlap with both — urea, lactic acid, salicylic acid.
Two things are worth knowing first.
One, it is common and often settles by itself. It is more frequent around puberty and tends to lessen with age. So 'it got better after I used X' cannot be separated from what time would have done anyway.
Two, the redness and the bumps are different problems. Keratolytic ingredients reduce the roughness, but the redness around each follicle often stays. Trials measure the two separately.
The evidence here is thin. The best-designed randomised trial we verified is a sham-irradiation-controlled laser study, and on the topical side we found no trial looking at this concern on its own.
Salicylic acid
Salicylic Acid
Most acne trials used 30% peels performed in a clinic. What Korea allows as an acne functional claim is 0.5%, and only in rinse-off cleansers. There is a sixtyfold gap between those two numbers.
Urea
Urea
5% and 40% are effectively different products. At low concentrations it holds water; at high concentrations it dissolves keratin. A 40% cream beat 12% ammonium lactate at two weeks, and in a 167-person trial of a urea-containing cream the primary endpoint was missed (P = .088) while the other measures were significant.
Lactic acid
Lactic Acid
In a 1983 trial, a 12% lactate lotion, a 5% lactic acid lotion and a plain emollient all three significantly improved xerosis. The difference emerged one to two weeks after treatment stopped. And in the 1996 photodamage trial it beat vehicle on four forearm measures — more than glycolic acid managed in the same trial.
Clinical procedures related to this concern
Procedures are not listed alongside topical ingredients. They are not something you use at home.
In preparation.