The incidence of headache was reported in 21 studies from 19 published articles: Headache occurred in 10.55% (561/5320) of patients undergoing anti-IL-5 treatment and 8.99% (437/4860) placebo patients, 23% higher in the anti-IL-5 treatment group compared to the placebo group (RR: 1.23, 95%CI: 1.10–1.39, P = 0.224, I2 = 15.6%), presenting the highest prevalence in the benralizumab group (RR: 1.51, 95%CI: 1.22–1.86, P = 0.533, I2 = 0.0%) among all sub-treatment groups. The gene discussed is IL5; the disease is Headache.