The purpose of this study is to analyze the factors contributing to the occurrence of systemic toxicity in patients injured after skin exposure to hydrofluoric acid (HFA) and to present guidelines for active treatment intervention based on this analysis. Data were acquired from EMBASE, PubMed, and Cochrane library for individual participant data (IPD) meta-analysis. Key searching terms included calcium gluconate (CAG), hydrofluoric acid, and case. This research consisted of case studies published between 1979 and 2020. Systemic toxicity was set as the main outcome. Data sets from 50 case studies (N = 125 participants) were analyzed. Multivariate binary logistic regression analyses of IPD found significant association effect of the total body surface area (TBSA) burned, indicating systemic toxicity {Regression coefficient estimate, 0.82; Standard error, 0.41; Odds ratio, 2.28; [95% confidence interval, 1.03 - 5.06], and p = 0.0424}. The optimal cut-off point (sensitivity; specificity) of the receiver operating characteristic curve of the total body surface area (TBSA) burned for contributing occurrence of systemic toxicity was 2.38(0.875; 0.959). IPD meta-analysis indicates that existing evidence supports the positive proportional association of the TBSA burned for systemic toxicity. If the TBSA burned (%) in patients exposed to hydrofluoric acid is greater than 2.38, early aggressive treatment intervention, including decontamination and various CAG application, should be recommended as the guideline.