Background: Dementia caregiving has been associated with a range of adverse effects on the physical health of the caregiver. However, the specific mechanisms underlying the relationship between dementia caregiver stress and ill health remain unclear. Objective: The aim of this study was to investigate, using available prospective data, the relationship between perceived stress (burden) and pre-clinical indices of ill-health (cortisol awakening response and secretory immunoglobulin A) amongst dementia caregivers. The potential moderating effect of social support on the perceived stress-physiological stress/health relationship was also explored. Methods: Participants (N = 31) were caregivers of community-dwelling older adults living with dementia who were enroled in a psychoeducation support program and provided data (study questionnaire and saliva samples) at two timepoints (T1 and T2), 10 weeks apart. Hierarchical regressions were used to determine if changes in stress and social support predicted change in each of the physiological outcomes. Results: Findings indicate that caregivers with more hours of care at T1, or with greater satisfaction with social support, were more likely to exhibit an adaptive cortisol awakening response at T2. Moreover, social support was found to buffer the effect of caregiver stress and hours of caregiving on the cortisol awakening response. Conclusions: Implications for future interventions targeting caregiver health are discussed.