SSRIs — Adverse Effects & Safety
A teenager starting fluoxetine whose parent asks "why does the label warn about suicide?" deserves a precise answer — and so does the NCLEX.
Core Concept
SSRIs carry a black box warning for increased suicidality in children, adolescents, and young adults under 25, especially during the first 1–4 weeks when energy returns before mood lifts. Monitor closely at initiation and every dose change. Common adverse effects include GI upset (nausea, diarrhea), sexual dysfunction, insomnia or drowsiness, weight changes, and CNS activation or agitation. Serotonin syndrome is the life-threatening emergency: it occurs when serotonin accumulates excessively, typically from combining an SSRI with another serotonergic agent (MAOIs, tramadol, triptans, St. John's wort, linezolid). The classic triad is altered mental status (agitation, confusion), autonomic instability (hyperthermia, tachycardia, diaphoresis), and neuromuscular hyperactivity (clonus, hyperreflexia, tremor). Onset is rapid — often within hours. Treatment is discontinuation of the offending agents and supportive care; cyproheptadine is the serotonin antagonist used. A washout period is required between MAOIs and SSRIs — at least 14 days in most cases, though fluoxetine requires a 5-week washout before starting an MAOI due to its long-acting metabolite. Abrupt discontinuation causes SSRI discontinuation syndrome — dizziness, irritability, paresthesias ("brain zaps"), flu-like symptoms — so taper gradually.
Watch Out For
Don't confuse serotonin syndrome (hyperthermia, clonus, rapid onset) with neuroleptic malignant syndrome (lead-pipe rigidity, slower onset, tied to antipsychotics). Students often mistake the black box warning as a contraindication — it's a monitoring mandate, not a prohibition. Discontinuation syndrome is uncomfortable but not dangerous; serotonin syndrome is a medical emergency requiring immediate intervention.
Clinical Pearl
Serotonin syndrome = HOT and TWITCHY (hyperthermia, clonus, hyperreflexia). NMS = HOT and STIFF (rigidity, elevated CK). The movement pattern tells you which one.
Test Your Knowledge
3 quick questions — see how well you understood SSRIs — Adverse Effects & Safety