There is no exact explanation for the increase in allergic diseases that occurred since the last two decades. An increased allergen exposure and/or a decreased bacterial load cannot explain the phenomenon completely. Other causal factors that rose at the beginning of the 1980s must be taken into consideration. Important changes at that time in our management of children were the worldwide switch from aspirin to paracetamol, the introduction of broad-spectrum antibiotics such as cephalosporins and the advice to avoid dust and pets in newborns from allergic families. General application of these new approaches, in itself or in combination, might be responsible, at least in part, for the increase of allergic diseases in children.