Amiloride HCl dihydrate is primarily used in medical treatments as a potassium-sparing diuretic. It is commonly prescribed to manage conditions such as hypertension and heart failure, where it helps reduce fluid retention without causing significant potassium loss. This makes it particularly beneficial for patients at risk of hypokalemia. Additionally, it is sometimes used in combination with other diuretics to enhance their effectiveness while mitigating side effects related to electrolyte imbalance. Beyond its cardiovascular applications, it is also utilized in research settings to study sodium channels due to its ability to inhibit epithelial sodium channel activity.