<p>If Chloramphenicol is absorbed from eye when taking anticoagulants e.g. warfarin, there may be an increase in the effect of this medicine. Action of Chloramphenicol will be inhibited if given simultaneously with Phenobarbital. The therapeutic efficacy of Dexamethasone may be reduced with the concomitant administration of phenytoin, phenobarbitone, ephedrine and rifampicin</p>