INTRODUCTION: Economic evaluations typically focus solely on patient-specific costs with economic spillovers to informal caregivers less frequently evaluated. This may systematically underestimate the burden resulting from disease. AREAS COVERED: Cost-of-illness (COI) analyses that identified costs borne to caregiver(s) were identified using PubMed and Embase. We extracted study characteristics, clinical condition, costs, and cost methods. To compare caregiver costs reported across studies, estimated a single 'annual caregiver cost' amount in 2021 USD. EXPERT OPINION: A total of 51 studies met our search criteria for inclusion with estimates ranging from $30 - $86,543. The majority (63%, 32/51) of studies estimated caregiver time costs with fewer studies reporting productivity or other types of costs. Caregiver costs were frequently reported descriptively (69%, 35/51), with fewer studies reporting more rigorous methods of estimating costs. Only 27% (14/51) of studies included used an incremental analysis approach for caregiver costs. In a subgroup analysis of dementia-focused studies (n = 16), we found the average annual cost of caregiving time for patients with dementia was $30,562, ranging from $4,914 to $86,543. We identified a wide range in annual caregiver cost estimates, even when limiting by condition and cost type.