Chronic migraine affects 2 % of the population and has substantial impact on quality of life and considerable burden on healthcare resources. 50-80 % patients with chronic migraine have excessive consumption of analgesic medications. Withdrawal of analgesics is often advised before commencing preventive treatments. However, some headache experts recommend preventive treatments alongside analgesic withdrawal. 434 patients with chronic migraine attending the Hull Headache Clinic who received OnabotulinumtoxinA as preventive treatment were stratified to those with or without analgesic overuse. Data was collected through a dedicated headache diary and analysed for headache and migraine days reduction and for an increment in headache-free days in the month post treatment. The data shows no difference in the therapeutic outcome in patients with or without analgesic overuse with substantial reduction in headache and migraine days and an increment in headache-free days in both groups in a real-life clinical setting. OnabotulinumtoxinA is equally effective in patients with chronic migraine with or without analgesic overuse.