The allergic object-relation and operational thinking are two psychosomatic concepts taken up here from the angle of the failure of negation. The allergic object-relation is a defensive system against object-loss which is the precondition of hallucinatory wish-fulfilment in the presence of the object. The prevalence of the pair incorporation/excorporation over the pair introjection/projection hinders the attribution of judgment. Excorporation proves to be the major defence mechanism and is noticeable in the allergic crisis of somatization as an attempt to discharge excitation in the case of conflict. If this is insufficient, there is a danger of an operational regression with its attendant risk of somatic disorganization. The operational mode of functioning is the result of a hypercathexis of the judgment of existence due to the failure of the judgment of attribution. A psychotherapy session with an adolescent girl with polymorphic allergic symptoms illustrates these theoretical proposals.