Discontinuation Syndrome — MRCPsych Paper B MCQ

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EasyMood DisordersDiscontinuation SyndromeMRCPsych Paper B

A patient with depression in remission abruptly stops paroxetine. Three days later, they develop dizziness, nausea, irritability and brief electric-shock-like sensations in the head. Their mood remains stable. What is the most likely explanation?

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Correct answer: A — Antidepressant withdrawal syndrome

The correct answer is A, antidepressant withdrawal syndrome, also called discontinuation syndrome. Abrupt cessation, onset within three days, dizziness, nausea, irritability and characteristic electric-shock sensations strongly support this diagnosis. Paroxetine is particularly associated with withdrawal symptoms. Relapse is less likely because it does not usually begin immediately after stopping an antidepressant and the patient’s mood remains stable. Serotonin syndrome and paroxetine toxicity occur with serotonergic exposure rather than withdrawal and would more typically involve features such as autonomic instability, hyperreflexia or clonus. Hyponatraemia does not characteristically cause electric-shock sensations. Mild withdrawal is generally monitored with reassurance; if symptoms are severe, NICE advises considering reinstatement at the previous dose followed by a slower, smaller-step taper.

Reference: NICE. Depression in adults: treatment and management (NG222), recommendations 1.4.13–1.4.21: Stopping antidepressant medication. 2022. https://www.nice.org.uk/guidance/ng222/chapter/Recommendations