Significant differences in IL‐6 levels were observed between OSCC and PML/C patients in both serum and saliva. In conclusion, our study indicates that the pro‐inflammatory cytokine IL‐6 is heightened in the saliva of OSCC patients compared to PMD individuals and controls. These findings suggest potential diagnostic or prognostic significance for IL‐6 in OSCC. Here, IL6 is linked to progressive multifocal leukoencephalopathy.