Abstract Background Erenumab is a monoclonal antibody specifically targeting the CGRP-receptor. Several studies showed efficacy and safety in patients with migraine. Less is known regarding dosage increase, especially in a difficult to treat patients. The aim of the study is to evaluate the increased dosage under real world conditions with particular focus on 70 mg non-responders. Methods In a retrospective analysis, patients treated in tertiary headache centers (Halle or Jena, Germany) receiving 70 mg erenumab for at least 3 months with a dosage increase to 140 mg were analyzed. Data were evaluated regarding headache days, intake of acute medication, previous prophylaxis, and medication overuse. Baseline and all treatment intervals were determined as three-month periods. Results Datasets of 52 migraine patients (90.4% women) aged between 22 and 78 years (mean 50.4 years, SD 12.1 years) were analyzed. At baseline (mean headache-days 15.67 ± 6.37) 51.9% met criteria for chronic migraine and 56% were currently overusing acute medication. While therapy with 70 mg showed significant improvement in headache days and 50% response, further improvement was not achieved for therapy escalation to 140 mg. The same applies to the secondary endpoints and covers the entire study population as well as the subgroups of chronic and episodic migraine. The 50% response of the 70 mg non-responders for escalation was only 5.14%. Conclusions In this difficult-to-treat patient cohort we reconfirmed the effectiveness of erenumab, but could not detect any additional benefit for a dosage escalation from 70 mg to 140 mg erenumab.