Cluster headache (CH) is associated with the most severe pain of the primary headache disorders. Barriers to optimal care include misdiagnosis, diagnostic delay, undertreatment, and mismanagement. Medication-over-use headache (MOH) may further complicate CH and may present as increased CH frequency or development of a background headache, which may be featureless or have some migrainous quality. A personal or familial history of migraine appears to be strongly associated with the development of MOH in CH, at least with the phenotype of background headache. Patients with CH, especially those with a personal and/or family history of migraine, must be carefully monitored for MOH, and medication withdrawal should be considered if a CH patient presents with features of MOH.