Finely ground oats: an FDA-recognized skin protectant for itch and minor irritation, with small eczema trials. Kind to most skin, but can sensitize infants.
Colloidal oatmeal is whole oat kernel ground very fine so it disperses in water. Its starches and beta-glucan form a protective, water-holding film; avenanthramides and other phenols calm inflammation and itch; saponins cleanse gently. In the US it is one of the few botanical ingredients approved as an over-the-counter skin protectant, for temporary relief of itch and irritation from rashes, eczema, poison ivy and insect bites.
Labels list it as 'colloidal oatmeal' when it is the regulated active and often as 'Avena sativa kernel flour' when used as a cosmetic ingredient — essentially the same material, though only the drug version must meet the pharmacopeia standard.
The FDA recognizes it as safe and effective as a skin protectant. Small trials, mostly from one manufacturer and without placebo arms, show 1% colloidal oatmeal creams improve eczema severity, itch, dryness and barrier measures within days to two weeks, and lab work explains the anti-inflammatory effect.
Reviews colloidal oatmeal's chemistry and its regulation as an FDA-monograph skin protectant: starches and beta-glucan protect and hold water, phenols are antioxidant and anti-inflammatory, and saponins cleanse. Written by manufacturer scientists.
Colloidal oatmeal extracts reduced inflammatory signals in lab tests, and in an investigator-blinded study of 29 women with itchy, dry lower legs, a colloidal oatmeal lotion improved dryness, scaling, roughness and itch.
In two single-arm studies (29 and 30 people) with mild to moderate eczema, a 1% colloidal oatmeal cream used for 14 days improved eczema severity, itch, hydration and water loss, with few adverse events.
Of 302 children with eczema referred for allergy testing, 14.6% had positive oat patch tests and 19.2% positive prick tests; 32% of oat-cream users were patch-test positive versus 0% of non-users. The authors suggest avoiding oat-protein products in infants with eczema.