Background: Hyperthermia is an undesirable implication in patients undergoing gastric lavage which can cause increasing of heart rate and vascular constriction through falling of body temperature and shivering. Then, this study has been performed with the aim of determining the effect of isothermal lavation serum on accession level of shivering in patients under lavage surgery. Materials and Methods: In this clinical trial study, 96 patients undergoing gastric lavage in Kerman Seyedoshohda hospital from Mordad to Aban of 1394 were randomly assigned to the intervention group (46 persons, receiving isothermal serum) and control group (46 persons, receiving serum with room temperature). During gastric lavage, accession of shivering and hemodynamic parameters including blood pressure (systolic and diastolic), heart rate, body central temperature and blood Oxygenation rate were checked and recorded. Data was analyzed using descriptive and analytical statistics in SPSS 22 software. Results: The results of the present study showed that there is a significant relation between shivering intensity and serum temperature. Patients' central temperature, diastolic blood pressure and heart rate during gastric lavage in test group were higher than control group. Maximum shivering intensity frequency concerned first grade shivering intensity and minimum frequency was related to two and four grade. However, There was no significant difference about variables of systolic blood pressure and blood Oxygenation rate. Conclusion: Gastric lavage with isothermal serum causes prevention of reducing core body temperature and reduce shivering after gastric lavage in patients under lavage surgery. Therefore, the use of this method is recommended as a preventive measure.