Tolvaptan Tablets 15 mg are oral medications used to treat low sodium levels (hyponatremia) caused by conditions like SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion), heart failure, or liver cirrhosis. The active ingredient, tolvaptan, is a selective vasopressin V2-receptor antagonist that promotes the excretion of free water without losing sodium or other electrolytes, helping to safely raise serum sodium levels.