A superantigen selected from the group consisting of the staphylococcal enterotoxins G and I (SEG and SEI) and staphylococcal enterotoxin-like toxins M, N and O (SEIM, SEIN and SEIO), or a mixture thereof, for use in preventing, or reducing the risk of developing, atopic dermatitis in a human being. In such use, the superantigen is mucosally administrated to a neonate within 3 months after birth.