Antihistamine Drug Misuse and Dependency in Headache Patients: A Case Series in a Tertiary Care Headache Center

Aims: To report antihistamine abuse at a tertiary headache center including 6 patients who meet the criteria for substance abuse for intramuscular diphenhydramine (DPH).

Presentation of the Cases: Six patients were identified who were prescribed intramuscular DPH and developed escalating drug use. All patients were female, with a mean age of 40.6 (32-53), with diagnosis of medication overuse headache. Five had chronic migraine and 1 new daily persistent headache. All 6 patients were disabled. Three patients had history of misuse of other drugs including benztropine, hydromorphone and clonazepam. Comorbid psychiatric disorders included 3 patients with major depressive disorder, 2 with ADHD, 1 with post-traumatic stress disorder and social phobia. All of these patients had a history of receiving intravenous DPH as part of their migraine treatment to avoid complications from neuroleptics.

Discussion and Conclusion: A literature search revealed eight case reports of DPH abuse including a total of nine patients, published between 1986 and 2014. Medical charts were reviewed at Jefferson Headache centre and identified 6 patients with intramuscular DHP abuse. Clinicians treating migraine should be aware of potential risk for DPH abuse. Intramuscular and intravenous forms of the drug should be limited to inpatient use, if possible, and should be avoided in patients with history of drug abuse and medication overuse.