Several studies have shown that there are notable benefits in adding a long acting beta 2-agonist to an inhaled corticosteroid. Particularly, long acting beta 2-agonists allow to reduce the amount of steroid that is required to induce a specific response and, consequently, its possible side effects. Currently the pharmaceutical market promotes, and physicians tend in any case to privilege, the use of fixed combinations for the treatment of the asthmatic patient and this also in the first phases of the illness. Nevertheless, for the majority of patients with mild to moderate asthma, it seems more reasonable to optimize the dose of the inhaled steroid before considering the addition of a long-acting beta 2-agonist, and use this latter on an 'as needed' basis if its pharmacodynamic characteristics allow it. Use of combinations is the more reasonable therapeutic choice for patients with a more severe pathological picture, who, despite the optimized dosage of the inhaled glucocorticoid, also require a long acting beta 2-agonist. After having verified the stability of the clinical control, it is possible to continue with the combined therapy provided, however, that this allows the treatment of the patient with the lowest dose of corticosteroid able to prevent, as far as is possible, exacerbations. Asthma exacerbations are less frequent with this therapy, but when they appear it is necessary to be immediately able to increase and, sometimes, also maximize the dosage of corticosteroid without being forced to double, or even triple, the dose of the long acting beta 2-agonist unless there is a real need--and which probably, rather, would induce unwanted side effects.