Higher frequency of adverse events w/ ACE inhibitors, ARBs or aliskiren. Potential interaction w/ diuretics; lithium; K-sparing diuretics, K supplements, salt substitutes containing K & other substances that may increase K levels; NSAIDs or selective COX-2 inhibitors; anticonvulsants (eg, carbamazepine, phenobarb, phenytoin, fosphenytoin, primidone); St. John's wort; nitroglycerin & other nitrates, or other vasodilators; medicines for HIV/AIDS (eg, ritonavir, indinavir, nelfinavir); antifungals (eg, ketoconazole, itraconazole); antibacterials (eg, rifampicin, erythromycin, clarithromycin, telithromycin); verapamil, diltiazem; simvastatin; dantrolene; ciclosporin. Increased blood levels of amlodipine w/ grapefruit or grapefruit juice.