Human topical research · n=20
Do urea/ammonium lactate combinations achieve better skin protection and hydration than either component alone?
Skin pharmacology and applied skin physiology · 2002
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Urea alone and urea/ammonium-lactate mixtures improved hydration and barrier measures. Abstract does not report significant improvement for ammonium lactate alone. 20 healthy subjects and wash challenge. Combination improvements cannot be assigned to lactate alone; no unsupported positive isolated claim.
Checked against the published abstract on Oct 1, 2026. Source 1 ↗Source 2 ↗
Abstract
Twenty subjects with healthy skin were treated with the following formulations for two weeks: drug-free W/O vehicle, 5% ammonium lactate (CAS 52003-58-4) in W/O vehicle, 5% urea (CAS 57-13-6) in W/O vehicle, 3% ammonium lactate + 3% urea in W/O vehicle, 5% ammonium lactate + 5% urea in W/O vehicle. These formulations were applied in randomized order to 6 test areas on the forearms; one area was left untreated. Repetitive washings were additionally performed in the second treatment week. TEWL, stratum corneum water content (corneometry-determined electrical capacitance), and cutaneous blood flow (laser Doppler) were measured at baseline, day 7, and day 14. 5% urea and both ammonium lactate/urea combinations produced significant stratum corneum hydration and improved stratum corneum barrier function; there were no significant differences between these three treatments.
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