In secondary analyses conducted among subsamples of patients, there was a significant association between hydroxyzine use and a faster decrease in biological inflammatory markers associated with COVID-19-related mortality, including the neutrophil-to-lymphocyte ratio (NLR), the lymphocyte-to-C-reactive protein ratio (LCRP), and circulating IL-6 levels (all p < 0.016), with a significant dose−effect relationship for the NLR and LCRP (both p < 0.037). The gene discussed is IL6; the disease is COVID-19.