The infectious complications are sometimes one of the ransons to be paid during the corticotherapy because of the immunodepression induced by the corticosteroids over the different stages of anti-infectious immunity. These many things are altered: the phagocytosis and bactericidis, the immunity of cellular mediation, the antibody and interferon production. On the contrary, the corticotherapy has no effect on the complement. This inequal attack of immunity defences against the infection explains the type of infection noticed during the corticotherapy