Patients who developed post-herpetic neuralgia after herpes zoster had significantly higher levels of IL-6 in serum than those with herpes zoster who did not develop neuralgia; both groups had higher levels of IL-6, IL-1β, TNF, and IL-8 than controls; and pain severity in neuralgia correlated positively with IL-6 levels [83]. This evidence concerns the gene CXCL8 and neuralgia.