This study examined the effects of tourist non-selective dumping of refuse on household health expenditure in Adamawa State, Nigeria. A mixed-method research design was adopted, combining quantitative and qualitative approaches. Multi-stage sampling technique was used to select 400 households from three local government areas (Yola North, Yola South, and Madagali) in Adamawa State. Data were collected through structured questionnaires administered using mobile-based KoboToolKit, complemented by 24 in-depth interviews with household heads and community stakeholders. Quantitative data were analysed using descriptive statistics and spatial regression analysis, while qualitative data were subjected to thematic analysis. The results showed that tourist non-selective dumping of refuse is prevalent in the study area, with 91.1% of respondents aware of the practice and 48.7% living within 500 metres of a dumping site. Malaria (81.7%), typhoid fever (51.8%), diarrhoea (42.9%), and cholera (22.5%) were the most reported health conditions among households. Households spent an average of ₦12,450 monthly on health, with 34.6% incurring additional expenditures of ₦5,000–₦10,000 due to waste-related illnesses. Spatial regression analysis revealed a statistically significant positive relationship between proximity to dumping sites and household health expenditure (β = 0.342, p < 0.01), with households within 500 metres of a dumping site spending an average of ₦8,450 more per month on health than those living beyond 1 km. Socioeconomic factors significantly mediated the relationship between refuse dumping and household health expenditure, with income (β = -0.412, p < 0.01) and education (β = -0.286, p < 0.01) significantly reducing health expenditure, while household size (β = 0.324, p < 0.01) and age (β = 0.134, p < 0.05) increased it. Environmental effects were severe, with drainage blockage (52.4% very severe) and water contamination (46.1% very severe) being the most reported. All four null hypotheses tested were rejected, confirming that tourist non-selective dumping of refuse has significant effects on household health, health expenditure, and the environment. Based on the findings, it was recommended that government should strengthen environmental laws and enforcement, invest in modern waste management infrastructure, integrate waste management into tourism development policies, and implement social protection programs for vulnerable households. Community-based waste management initiatives, public awareness campaigns, and sustainable practices by tour operators were also recommended.