A new technique to evaluate dermal irritation caused by topical products was described. Twenty subjects with steroid-responsive dermatoses were enrolled. A 3 cm2 area of normal skin was abraded by a new razor using 10 upward strokes. Hydrocortisone butyrate 0.1% lipocream was then applied to the area. Patients rated the irritation on a 0-4 scale (where 0=no symptoms and 4=intolerable). Fifty-five per cent of subjects had no irritation; the average score was 0.65 (less than mild). Twenty-five per cent of subjects had mild irritation, 20% had medium irritation and none had intolerable irritation. This assay quantified even minimal irritation and may be useful to determine the irritation risk of topical medicaments ...