In general, most physicians are not familiar with headache syndromes induced by the use of illicit drugs such as cocaine, marijuana, and opioids. Some patients can develop thunderclap headache and reversible cerebral vasoconstriction syndrome. In this clinical summary, Shuu-Jiun Wang, Professor of Clinical Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan, provides an update on the underlying pathophysiology and reviews the clinical aspects of headache syndromes induced by illicit drugs in light of the criteria presented in the International Classification of Headache Disorders, 2nd edition (ICHD-2), 2004. This updated summary includes a recent report on emergency department patients who took energy drinks. Headache was one of their adverse events, and of note, some patients reported purposely ingesting energy drinks with illicit drugs.