Forgoing healthcare for economic reasons has been previously associated with adverse health outcomes, including a higher risk of hospitalization, a lower quality of life, and worse self-reported health. However, the exact cause-to-effect relation between forgoing healthcare and health-related outcomes has been insufficiently described. Here, we investigate the prospective health consequences of forgoing healthcare for economic reasons using data from "ReBus" (N = 400), a prospective study examining the health consequences of forgoing healthcare (Baseline: 2008-2013, Follow-up: 2014-2016). Using regression models, we explored the baseline determinants of forgoing healthcare, including socioeconomic, demographic, and pre-existing health-risk factors, and examined the associations between forgoing healthcare at baseline and health deterioration at follow-up, using highly pertinent biomarkers (glucose, glycated hemoglobin, lipids, blood pressure) and SF-36 questionnaire data. Low income, low occupation, low education, and smoking were associated with higher odds of forgoing healthcare at baseline. Forgoing healthcare for economic reasons at baseline was subsequently related to detrimental changes in glucose, high-density lipoprotein cholesterol (HDL), and blood pressure (BP) at follow-up, independently of baseline socioeconomic factors (Glucose-β = 0.19, 95%CI[0.03;0.34], HDL-β = -0.07, 95%CI[-0.14;0.01], BP-β = 3.30, 95%CI[-0.01;6.60]). Moreover, we found strong associations between forgoing healthcare and adverse SF-36 health scores at follow-up, with individuals forgoing healthcare systematically displaying worse health scores (6%-11% lower scores). For the first time, we show that forgoing healthcare for economic reasons predicts adverse health-related consequences 2-8 years later. Our findings shall further encourage the implementation of public health measures aimed at identifying individuals who forgo healthcare and preventing the adverse health consequences of unmet medical needs.