Anti-infective agents (erythromycin, ketoconazole): No clinically important adverse effects or changes in the QT interval corrected for rate (QTc) were reported after concomitant administration of erythromycin or ketoconazole with fexofenadine. Increases in fexofenadine plasma concentrations observed during the drug interaction studies.
Data from in vitro and in vivo studies in animals indicate that erythromycin and ketoconazole enhance absorption of concomitantly administered fexofenadine, possibly by affecting mechanisms of transport systems such as p-glycoprotein. Fexofenadine did not alter the pharmacokinetics of erythromycin or ketoconazole.
Antacids: Antacids containing aluminium and magnesium hydroxide have reduced the absorption of fexofenadine. Therefore, fexofenadine should not be taken closely in time with antacids containing aluminium and magnesium.