Introduction: In light of the increasing number of economic burden studies and heterogeneity in methodology and reporting standards, there is a need for robust evidence synthesis on an umbrella review level. Areas covered: We performed the first review of reviews of cost-of-illness studies in multiple sclerosis. Focusing on disaggregated costs by disease characteristics (disability level, relapse, disease course), we also characterized the underlying methodological evidence base of individual (primary) studies. Expert Commentary: We identified 17 reviews encompassing 111 unique primary studies, and a high degree of overlap across reviews. Costs were substantial, rising with disability level, relapse episodes, and disease progression. Disability was the key cost driver. Compared to mild disability, total costs for moderate disability were 1.4–2.3-fold higher and 1.8–2.9-fold higher for severe disability. With escalating disability, the share of costs outside the health system (indirect costs, informal care) increasingly outweighed the share of direct medical costs. Of all 111 primary studies, 72% gathered resource use/loss data by patient self-report. Associated costs were mostly reported by disability level (75%), followed by relapse (48%) and disease course (21%). In conclusion, although heterogeneity can make in-depth comparisons of costs across studies impossible, important patterns are broadly apparent.