Contraindications for Fluoxetine in a 14-Year-Old
Fluoxetine is contraindicated in adolescents who are taking or have taken monoamine oxidase inhibitors (MAOIs) within the past 14 days, who are taking pimozide or thioridazine, or who have a known hypersensitivity to fluoxetine. 1
Absolute Contraindications
Drug Interactions with Serious Risk
MAOIs: Concomitant use or use within 14 days of discontinuing an MAOI is absolutely contraindicated due to risk of serotonin syndrome, which can be fatal. 1 Similarly, at least 5 weeks must elapse after stopping fluoxetine before starting an MAOI due to fluoxetine's exceptionally long half-life (1-3 days for parent compound, 4-16 days for active metabolite norfluoxetine). 2, 1
Pimozide: Concurrent use is contraindicated due to risk of QTc prolongation and potential for fatal cardiac arrhythmias. 1
Thioridazine: This combination is contraindicated due to risk of serious ventricular arrhythmias and sudden death from elevated thioridazine plasma levels, as fluoxetine potently inhibits CYP2D6. 1 A minimum of 5 weeks must pass after fluoxetine discontinuation before thioridazine can be safely initiated. 1
Hypersensitivity
- Known hypersensitivity or allergic reaction to fluoxetine or any component of the formulation is an absolute contraindication. 1
Critical Safety Warnings Specific to Adolescents
Suicidality Monitoring
Close monitoring for suicidal ideation and behavior is mandatory in adolescents starting fluoxetine, particularly during the first few weeks of treatment and after any dose changes. 3, 1 The WHO guidelines specifically state that adolescents on fluoxetine should be monitored closely for suicide ideas/behavior. 3
Symptoms requiring immediate attention include new or worsening depression, anxiety, agitation, panic attacks, insomnia, irritability, hostility, impulsivity, akathisia, hypomania, or any abrupt behavioral changes—these may signal increased suicide risk. 1
Relative Contraindications and High-Risk Situations
Drug Interaction Concerns
Caution with any serotonergic agents: Combining fluoxetine with triptans, tramadol, tryptophan, or other serotonergic drugs increases risk of serotonin syndrome. 4, 1 Serotonin syndrome manifests within 24-48 hours as mental status changes, neuromuscular hyperactivity (tremors, hyperreflexia), autonomic hyperactivity (tachycardia, diaphoresis), and can be life-threatening. 4
Drugs metabolized by CYP2D6: Fluoxetine is a potent CYP2D6 inhibitor that can convert normal metabolizers into poor metabolizer phenotypes. 2, 1 This creates significant interaction risk with tricyclic antidepressants, most antipsychotics (phenothiazines, atypicals), antiarrhythmics (propafenone, flecainide), and other CYP2D6 substrates. 1
Bleeding risk: Concomitant use with NSAIDs, aspirin, warfarin, or other anticoagulants increases bleeding risk and requires careful monitoring. 1
Medical Conditions Requiring Caution
Hepatic dysfunction: Fluoxetine has nonlinear pharmacokinetics and should be used with extreme caution in patients with reduced hepatic metabolic capacity, as drug accumulation can occur. 5
Seizure disorders: While not an absolute contraindication, caution is warranted as fluoxetine can interact with anticonvulsants (phenytoin, carbamazepine), potentially causing elevated anticonvulsant levels and clinical toxicity. 1
Important Clinical Pitfalls
Do not use fluoxetine as first-line in children 6-12 years old with depression in non-specialist settings according to WHO guidelines. 3 However, fluoxetine may be considered for adolescents (ages 13+) with depressive episodes in non-specialist settings, though close monitoring is essential. 3
Pregnancy and breastfeeding: Patients should notify their physician if pregnant, planning pregnancy, or breastfeeding, as risk-benefit assessment is required. 1
Avoid abrupt discontinuation: Although fluoxetine's long half-life minimizes withdrawal syndrome compared to other SSRIs, gradual tapering over 6-10 weeks is recommended for long-term therapy. 4, 6