Hyponatremia overcorrection may lead to serious irreversible neurologic impairment. Although studies have sought to identify risk factors and optimal treatment regimens for hyponatremia, findings have been inconsistent, and current treatment guidelines provide recommendations that do not take into account patient-related factors. This study aimed to identify risk factors of hyponatremia overcorrection and assess the relationship between administered sodium dose and subsequent changes in serum sodium levels. This retrospective cohort study involved 212 patients with hyponatremia admitted to the emergency department of a tertiary medical center. The primary study outcome was hyponatremia overcorrection, defined as >12 mEq/L increase of serum sodium at 12 hours after baseline. The secondary study outcome was hyponatremia overcorrection defined as >8 mEq/L increase of serum sodium at 12 hours after baseline. Overcorrection of more than 8 mEq/L and 12 mEq/L at 12 hours occurred in 39 (18.4%) and 16 (7.5%) patients, respectively. Low urine osmolality (<150 mOsm/kg) and total sodium dose of >4.6 mEq/kg over 12 hours were significant risk factors of hyponatremia overcorrection on multivariable Logistic regression analysis (Table 1). Serum sodium changes were significantly higher in the group with >4.6 mEq/kg/12hr compared to that of the >3.4 mEq/kg/12hr group (9.4 ± 5.3 mEq/L vs. 5.1 ± 4.0 mEq/L, P = 0.001) (Figure 1). Low urine osmolality and total sodium dose above 4.6 mEq/kg/12hr were significant risk factors for overcorrection in patients with hyponatremia. Calculating the total sodium dose may be useful in preventing hyponatremia overcorrection.