Dengue is mostly considered an acute illness with three phases: febrile, critical with possible hemorrhagic manifestations, and recovery. But some patients present persistent symptoms, including fatigue and depression, as acknowledged by the World Health Organization. If persistent symptoms affect a non-negligible share of patients, the burden of dengue will be underestimated. On the basis of a systematic literature review and econometric modeling, we found a significant relationship between the share of patients reporting persisting symptoms and time. We updated estimates of the economic burden of dengue in Mexico, addressing uncertainty in productivity loss and incremental expenses using Monte Carlo simulations. Persistent symptoms represent annually about US$22.6 (95% certainty level [CL]: US$13–US$29) million in incremental costs and 28.2 (95% CL: 21.6–36.2) additional disability-adjusted life years per million population, or 13% and 43% increases over previous estimates, respectively. Although our estimates have uncertainty from limited data, they show a substantial, unmeasured burden. Similar patterns likely extend to other dengue-endemic countries.