Lithium is the main cause of secondary nephrogenic diabetes insipidus, occurring in approximately 20% of patients that use this drug chronically.Amiloride has been proposed as an alternative for those patients who develop lithium-induced nephrogenic diabetes insipidus in whom drug suspension is not the best option.This drug prevents the entry of lithium to the nephron by blocking the epithelial sodium channel (ENaC) in the main cells.The suggested doses are 5mg twice a day, and can be combined with hydrochlorothiazide at a dose of 50mg per day.Numerous studies have demonstrated the beneficial effect of amiloride on lithium-induced nephrogenic diabetes insipidus, however, its long-term safety and effectiveness have not been evaluated.