Salmeterol and other beta-2 agonist with corticosteroids, diuretics, or xanthines increase the risk of hypokalemia, and monitoring potassium concentrations is recommended in severe asthma, where such combination therapy is the rule. For an outline of interactions associated with sympathomimetics in general.
Fluticasone concurrent use of barbiturates, carbamazepine, phenytoin. primidone, or rifampicin may enhance the metabolism and reduce the effects of systemic corticosteroids. Conversely, oral contraceptives or ritonavir may increase plasma concentrations of corticosteroids. Use of corticosteroids with potassium depleting diuretics, such as thiazides or furosemide may cause excessive potassium loss.