A p38 MAPK inhibitor for use in the treatment or prevention of severe influenza in a human patient. In some embodiments, the severe influenza maybe characterised by hypercytokinemia involving elevated levels of one or more pro-inflammatory cytokines. The p38 MAP kinase inhibitor may act to inhibit the release of such pro-inflammatory mediators from endothelial cells. In some embodiments, the p38 MAP kinase inhibitor may inhibit the release of IP 10 from endothelial cells, preferably in a dose-dependent manner.