This retrospective observational study aimed to investigate the risk of serum sodium concentration in patients treated with terlipressin and attempted to explore the factors associated with serum sodium concentration. We included 17 patients with portal hypertension treated with terlipressin (Group 1), 7 with portal hypertension treated with somatostatin/octreotide (Group 2), 20 with acute non-variceal gastrointestinal bleeding treated with somatostatin/octreotide (Group 3), and 19 with acute pancreatitis treated with somatostatin/octreotide (Group 4). In all groups, serum sodium concentration at baseline was not significantly different from the lowest value during the infusion of terlipressin, somatostatin, or octreotide (Group 1: 136.95 AE 4.68 versus 135.52 AE 4.79, p = 0.426; Group 2: 139.64 AE 3.86 versus 138.41 AE 5.34, p =0.813; Group 3: 138.02 AE 4.08 versus 137.69 AE 3.11, p = 0.630; Group 4: 135.96 AE 6.87 versus 134.60 AE 3.40, p = 0.098). The rate of serum sodium concentration reduction in Group 1 (8/17) was not significantly different from Group 2 (3/7, p =1.000),Group3 (11/20, p = 0.746), or Group 4 (14/19, p = 0.171). Age, sex, baseline MELD and Child-Pugh scores, cDDD value and duration of terlipressin, blood transfusion, and diuretics and paracentesis during terlipressin were not significantly associated with serum sodium concentration reduction in Group 1. In conclusion, serum sodium concentration is often reduced in patients treated with terlipressin. However, the association of sodium concentration reduction with terlipressin should be clarified.