<p>The third Sustainable Development Goal (SDG) aims to enable everyone to live in good health and to promote the well-being of all. However, despite the various efforts made to achieve this goal, sub-Saharan Africa (SSA) is still characterised by low human longevity. To increase longevity, authors have stressed the importance of public spending on health. However, continuous borrowing and servicing of public debt deprive the SSA of funds that could be devoted to public spending on health. In this context, this research provides evidence on how public debt mitigates the effect of public health spending on human longevity in SSA. Using public indebtedness as a transition variable, this paper uses dynamic panel threshold regression to analyse the effects of public health expenditure on human longevity in 27 SSA countries covering the period 2010–2020. The results reveal a nonlinear relationship between public health spending and human longevity. This research shows that a level of public debt greater than 35.1348% of gross domestic product leads to a reduction in public spending on health and a decrease in human longevity. In view of these results, the governments of SSA countries must strengthen prudent budgetary measures to reduce public debt and increase the mobilisation of domestic resources to finance the health sector.</p>