SSRI Activation Syndrome — MRCPsych Paper B MCQ

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ModerateMood DisordersSSRI Activation SyndromeMRCPsych Paper B

A 35-year-old woman with a major depressive episode starts fluoxetine. Seven days later, she reports feeling markedly more anxious and restless and is having difficulty sleeping. Her depressive symptoms are unchanged. She is afebrile, with normal observations, and has no confusion, diaphoresis, diarrhoea, clonus, muscle rigidity or rash. Which is the most likely explanation?

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Correct answer: C — SSRI-induced activation syndrome

This is **SSRI-induced activation syndrome**, also termed jitteriness/anxiety syndrome. It presents soon after starting an SSRI with increased anxiety, agitation or restlessness and sleep disturbance. The close temporal relationship and absence of hyperthermia, autonomic instability, gastrointestinal symptoms, clonus or rigidity argue against serotonin syndrome. These symptoms do not represent therapeutic response because her depression has not improved, and treatment failure cannot be concluded after only 1 week. A hypersensitivity reaction would be suggested by features such as rash, urticaria, angioedema or systemic allergic manifestations. Activation may be transient, but marked or persistent agitation warrants clinical review, including assessment of suicidal ideation. Claims that it predictably resolves within 2 weeks or is reliably more common with particular SSRIs or in anxious patients are insufficiently established.

Reference: National Institute for Health and Care Excellence. Generalised anxiety disorder and panic disorder in adults: management, CG113, recommendation 1.2.28; updated 2020. https://www.nice.org.uk/guidance/cg113/chapter/Recommendations