Long-term frequent use of acute pain medication for the treatment of headaches has paradoxically been shown to increase the frequency of headaches. So-called medication-overuse headache (MOH) is particularly problematic in patients with migraine who overuse triptans and opioids. Prevention through education remains the most important management strategy. Once established, MOH can be difficult to treat. Although complete or near-complete withdrawal of acute pain medication for 8-12 weeks has been shown to benefit most patients, this can be hard to achieve. The use of OnabotulinumtoxinA and drugs that target the calcitonin gene-related peptide system for the prevention of migraines have been shown to benefit patients with MOH. Furthermore, the use of novel acute pain medication for migraines, including Gepants and Ditans, which do not cause MOH, are likely to improve patient outcomes. In this review article we examine the following: the burden of MOH; who develops MOH; the pathophysiological mechanisms; and the treatment strategies.