Exogenous histamine aggravates eczema in a subgroup of patients with atopic dermatitis.

Food and beverages may contain high amounts of histamine and thus may cause symptoms after ingestion. The aim of this study was to investigate the role of ingested histamine in atopic dermatitis. Patients with atopic dermatitis had to maintain a histamine-free diet for one week. Consecutively, double-blind, placebo-controlled provocations were performed with histamine-hydrochloride and placebo. The clinical outcome was assessed by determination of the SCORAD. Before and 30 min after each provocation blood was collected for measurement of plasma histamine levels and diamine oxidase activity. Thirty-six patients with atopic dermatitis completed the diet. Twelve of 36 showed a significant improvement of the SCORAD after one week of the diet. After provocation tests 11 of 36 showed aggravation of eczema. Plasma histamine was significantly higher in patients with atopic dermatitis compared with controls (p><0.001), whereas diamine oxidase activity was similar in both groups. Our data indicate that ingestion of moderate or high amounts of histamine-hydrochloride may aggravate eczema in a subgroup of patients with atopic dermatitis. Plasma histamine and diamine oxidase activity were not associated with the clinical response to histamine.