These durations were statistically significantly and positively correlated with early concentrations of IL‐1β (ρ = 0.56, p = 0.003, Spearman), IL‐2 (ρ = 0.49, p = 0.007, Spearman), and IL‐21 (ρ = 0.44, p = 0.03, Spearman) (Figure 5), and more generally with the Th1–Th17 response, whereas an early elevation of Th2 cytokines (IL‐5, IL‐13) was statistically significantly and positively correlated with headache duration (ρ = 0.57, p = 0.003 and ρ = 0.65, p < 0.001, respectively, Spearman) (Figure 5). The gene discussed is IL21; the disease is Headache.