Objective:To develop a prediction model for the dosage of antivenom in patients envenomed by Trimeresurus stejnegeri (bamboo pit viper) using Lasso-Logistic regression.Methods:A retrospective cohort study was conducted including 165 patients with Trimeresurus stejnegeri bites admitted to the Emergency General Ward of Yangjiang Hospital Affiliated to Guangdong Medical University (Yangjiang People's Hospital) between October 31, 2021, and November 1, 2024. Data on demographic characteristics, key clinical signs, laboratory parameters, antivenom treatment regimen, and total antivenom dosage were collected. Predictive variables were selected using LASSO and Logistic regression methods. The prediction model was constructed using R software. Model calibration was assessed using the Hosmer-Lemeshow test, discriminative ability via the receiver operating characteristic (ROC) curve, and clinical utility using decision curve analysis.Results:Among the 165 enrolled patients, 71 received a total antivenom dose of ≤3 vials, and 94 received >3 vials. Six predictors for requiring >3 vials of antivenom were identified: pain severity, swelling degree, serum treatment regimen, 3P-test result, white blood cell count (WBC), and fibrinogen level (FIB). After comparing 22 prediction models incorporating 4 to 6 variables, the model comprising swelling degree, pain severity, WBC, and FIB was selected. The calibration curve indicated good agreement between predicted and actual risks. The area under the ROC curve (AUC) was 0.78 (95% CI: 0.71–0.85), demonstrating satisfactory discriminative ability for predicting whether the total antivenom dose exceeded 3 vials. Conclusions:The risk prediction model shows good performance in identifying whether the total antivenom dose exceeds 3 vials in Trimeresurus stejnegeri bite patients. It incorporates six readily available clinical variables: pain severity, swelling degree, serum regimen, 3P-test, WBC, and FIB. A model based on pain severity, swelling degree, WBC, and FIB can assist clinicians in predicting whether a patient will require more than 3 vials of antivenom after standard treatment.