Objective This study aims to analyse the effect of the discontinuation of anti-calcitonin gene-related peptide antibodies on monthly migraine days after 12 treatment months. Background Anti-calcitonin gene-related peptide antibodies have been a game changer in migraine prophylaxis. However, high treatment costs warrant reducing treatment duration to the essential minimum. Methods We collected data of patients with migraine who had received anti-calcitonin gene-related peptide antibodies and had received treatment for 12 months. Results We included 52 patients. The average number of monthly migraine days was 16 ± 7 days at baseline, 6 ± 6 in the third, and 5 ± 4 in the 12th treatment month. After treatment interruption, the number of monthly migraine days was 6 ± 4 days in the first month, 9 ± 4 days in the second, and 11 ± 5 days in the third month. Most patients (88.9%) restarted treatment. Conclusion Only little of the therapeutic effect of anti-calcitonin gene-related peptide antibodies outlasts their pharmacological effect. After treatment interruption, migraine frequency rose in most patients, and prophylaxis was required again in most cases. Limiting treatment to benefitting patients and confirming the need for prophylaxis periodically is reasonable. However, our data does not support the need for prescheduled treatment discontinuation after 12 months and a fixed duration of the treatment interruption of 3 months.