Chronic migraine has been linked to the excessive use of acute headache medications. Medication overuse (MO) is commonly considered the most significant risk factor for the progression of migraine from an episodic to a chronic condition. Managing MO is a challenge. Discontinuation of the acute medication can result in withdrawal headache, nausea, vomiting and sleep disturbances. This review summarizes the results from two similarly designed, randomized, placebo-controlled, multicentre studies of chronic migraine conducted in the USA and European Union. Both studies demonstrate the efficacy and safety of the migraine preventive medication, topiramate, for the treatment of chronic migraine in patient populations both with and without MO. These studies may have important implications for the future of chronic migraine management, suggesting that detoxification prior to initiating prophylactic therapy may not be required in all patients if MO is present.