The invention relates to a hypoallergenic dermatological or cosmeticcompositioncomprising an extract of aerial part(s) of oats harvested before earemergence, theextract comprising 2 to 15%wt of flavonoids and 0.2 to 2%wt of avenacosides AandB. Such a composition is useful in the treatment of skin diseases such asinflammatory dermatoses, acne, skin ageing, rosacea or reactive skins.