Activated monocytes/macrophages that produce a cytokine storm play an important role in the pathogenesis of dengue. Interleukin-18 (IL-18) is a proinflammatory cytokine produced by monocyte/macrophages that is increased during dengue. Ferritin is an acute-phase reactant and expressed by cells of the reticulo-endothelial system in response to infection by dengue virus. The aims of this study were to analyze the simultaneous expression of both IL-18 and ferritins in children infected by diverse serotypes of dengue virus (DENV) and determine their association with dengue severity. In this regard, children with dengue (n = 25) and healthy controls with similar age and sex (n = 20) were analyzed for circulating ferritin and cytokines. Monocytes were isolated by Hystopaque gradient and co-cultured with DENV-2. IL-18 and ferritin contents in blood, and IL-18 in culture supernatants were determined by ELISA. Increased levels of ferritin and IL-18 (p < 0.0001) were observed in dengue patients, not associated to NS1expression or type of infection (primary or secondary). Highest values of both molecules (p < 0.001) were observed in dengue with warning signs and severe dengue. Differential effect on IL-18/ferritin production was observed associated to viral serotype infection. There were no correlations between ferritin vs. IL-18 production, ferritin vs. NS1 status, and IL-18 vs. NS1 status. Viral-infected monocyte cultures showed increased production of IL-18 (p < 0.001). In conclusion, increased circulating ferritin and IL-18 are expressed in children infected by different serotypes of DENV associated with dengue severity.