Background <p>Opioid withdrawal is not typically associated with seizures or catatonia. However, the adulteration of illicit opioids like brown sugar with benzodiazepines can lead to unrecognised benzodiazepine dependence, thereby increasing the risk of withdrawal seizures. Postictal catatonia, although rare, may occur following generalised seizures and can mimic psychiatric or neurological disorders.</p> <p>Case Presentation.</p> <p>We report the case of a 26-year-old male with opioid dependence who experienced a generalized tonic–clonic seizure on the fourth day of opioid withdrawal. Following the seizure, he developed transient catatonic features—mutism, waxy flexibility, posturing, and mitgehen—without preceding psychiatric illness. Investigations were unremarkable, and catatonic symptoms resolved spontaneously within hours without pharmacological intervention. Given the clinical sequence and resolution, a diagnosis of postictal catatonia following a benzodiazepine withdrawal seizure was made.</p> Discussion <p>This case underscores the need to consider benzodiazepine adulteration in opioid users and to recognise postictal catatonia as a distinct, self-limiting entity. Differentiating it from primary catatonia or delirium is crucial to avoid unnecessary treatment with benzodiazepines or electroconvulsive therapy.</p> Conclusion <p>Clinicians should maintain a high index of suspicion for benzodiazepine adulteration in opioid users presenting with seizures. Awareness of postictal catatonia can prevent misdiagnosis and overtreatment, promoting appropriate and conservative management of this rare neuropsychiatric phenomenon.</p>