La
Lactic Acid
Lactic AcidExfoliant
An exfoliating acid, gentler than glycolic, that also pulls water into skin.
What it does
It exfoliates and pulls water into skin. People with sensitive skin often reach for it over glycolic acid.
The evidence, graded
strongIn a 21-day double-blind trial, 60 people with moderate to severe dry skin used a neutralized 12% lactate lotion, a 5% lactic acid lotion and a plain lotion without lactate. All three eased dryness. In the two weeks after people stopped, skin that had the 12% lactate lotion showed greater drops in dryness scores than skin that had the plain lotion or the 5% lotion.Dahl 1983 · Archives of Dermatology ↗
expert consensusUse retinol and AHAs like glycolic or lactic acid on alternate nights, or the acid in the morning and retinol at night: the acid and the retinoid each irritate skin on their own. In the one study of the pair Drop's sources describe, retinol with glycolic acid improved photoaged skin more than either alone; it measured results, not comfort. Splitting them is a careful default, not a proven rule: no study Drop has read measured their irritation together.Mukherjee 2006 · Clinical Interventions in Aging ↗
expert consensusAlternate tretinoin and the acid by night, or split them across the day. Tretinoin is described as the most potent of the retinoids, more irritating than retinol, and acids irritate on their own. No study Drop has read applied the two to the same skin, so that they compound is a careful assumption, not a measurement.Mukherjee 2006 · Clinical Interventions in Aging ↗
expert consensusAdd an AHA and salicylic acid one at a time, within a safety panel's limits: AHAs under 10% at pH 3.5 or higher, salicylic acid under 3%. The review says salicylic acid is not a beta hydroxy acid and doesn't act like one, despite the label. In one study 10% glycolic acid made skin more sun-sensitive and 2% salicylic acid did not. No source Drop has read tested the two used together, so Drop can't tell you the pair is safe or that it isn't.Kornhauser 2010 · Clinical and Cosmetic Investigative Dermatology ↗
expert consensusThe lactic acid study Drop read measured what 5% and 12% did for skin — firmness, thickness, smoothness, lines — and reported no irritation at all. So Drop can't tell you lactic acid is the gentler acid, and no study Drop has read put it on skin with a retinoid. Retinoids irritate on their own. Alternate nights to start.Smith 1996 · Journal of the American Academy of Dermatology ↗
expert consensusIn 2000 the EU’s Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP) found the data on AHAs too thin for a full safety assessment. On the precautionary principle, until the data were available, it suggested lactic acid up to a maximum level of 2.5% and a pH of 5 or higher. It recommended warnings to avoid the eyes and to avoid or protect from UV. In 2004 it found that AHA use does increase UV damage to the skin, and kept its 2000 position.SCCNFP 2000 · European Commission SCCNFP ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
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