Background: Individuals with Multiple Sclerosis (MS) often receive home health care, yet little research investigates the health of informal caregivers of individuals with MS. Methods: We tested a mediation model in which associations between caregiver stress and caregiver self-care were explained by each of four a priori caregiver health factors—caregiver negative affect, pain, tiredness, and functional limitations. Participants (n = 60 informal caregivers) were recruited online or in-person from March—July 2018, and completed an online survey assessing demographics and their caregiving experience. Results: After controlling for demographics, only caregiver tiredness mediated the association between caregiver stress and caregiver self-care. Therefore, caregiver tiredness may be an important construct for assessment, intervention, and future research, among caregivers of individuals with MS, and among anyone providing home health care. Conclusions: These findings have research, clinical, and policy implications.