OBJECTIVE: To examine whether detoxifying patients with medication-overuse headache can reduce long-term medication costs. BACKGROUND: Direct costs of medications in medication-overuse headache have been reported to be very high but have never been calculated on the basis of exact register data. Long-term economic savings obtained by detoxification have never been investigated. METHODS: We conducted a registry-based observational retrospective follow-up study on 336 medication-overuse headache patients treated and discharged from the Danish Headache Center over a 2-year period. By means of the Danish Register of Medicinal Product Statistics, we collected information on the costs and use of prescription-only medication 1 year before admission and 1 year after discharge from Danish Headache Center. RESULTS: The average medication costs per patient per year decreased with 24%, from US$971 before treatment to US$737 after (P = .001), and the average medication use decreased with 14.4% (P = .02). Savings were most pronounced for patients overusing triptans. In this group, the average medication costs per patient per year decreased with 43% (P