Substance use related cluster headache: A case series.

Background: Essential oils (EOs) with pro‐convulsant properties are known to cause seizures and may worsen migraine. Here we report five cases of cluster headache (CH) secondary to the usage of toothpastes containing pro‐convulsant EOs. Methods: Patients were identified from the headache clinics of three tertiary care hospitals in south India. Detailed history, examination, and brain magnetic resonance imaging were done in all patients. CH was diagnosed according to the International Classification of Headache Disorders, 3rd edition. Descriptive statistics were used to analyze data. Results: We had five cases of EO‐related CH (EORCH), from February 2020 to August 2021; three females and two males, with age ranging from 19 to 54 years. Three had new onset CH, while two had previous cluster attacks which had become refractory to medications for the past 1 year. The toothpastes contained EOs of camphor, eucalyptus, sage, thujone, clove, and fennel in various combinations. These toothpastes were used for a period of at least 3 months in those with new onset CH and for 12 months or more by those with chronic CH. After stopping the usage of these toothpastes, the CH attacks resolved completely within 5–10 days in all patients. In one patient we re‐challenged with the same toothpaste and got the CH attack after a period of 2 months. None of the patients had recurrence of CH attacks at follow‐up, ranging from 1 to 2 years. Conclusion: EOs with pro‐convulsive properties may trigger and sustain CH. Physicians may consider inquiring about the exposure to these pro‐convulsant EOs in patients with CH and may consider advising the discontinuation of products like toothpastes containing them as a possible means of CH remission. [ABSTRACT FROM AUTHOR]