What is the recommended fluvoxamine dosing schedule for treating obsessive‑compulsive disorder in adults and in children aged 8–17?

Fluvoxamine Dosing for Obsessive-Compulsive Disorder

For adults with OCD, start fluvoxamine at 50 mg once daily at bedtime, then increase by 50 mg every 4-7 days as tolerated up to 100-300 mg/day (maximum 300 mg/day), with doses above 100 mg split into two divided doses (larger dose at bedtime). 1

For children and adolescents aged 8-17 years, start at 25 mg once daily at bedtime, then increase by 25 mg every 4-7 days as tolerated, with maximum doses of 200 mg/day for children up to age 11 and 300 mg/day for adolescents, splitting doses above 50 mg into two divided doses (larger dose at bedtime). 1

Adult Dosing Schedule

• Initial dose: 50 mg at bedtime as a single daily dose 1
• Titration: Increase in 50 mg increments every 4-7 days based on tolerability 1
• Therapeutic range: 100-300 mg/day, established in controlled trials 1
• Maximum dose: 300 mg/day 1, 2
• Divided dosing: Total daily doses exceeding 100 mg should be split into two doses, with the larger dose given at bedtime 1

Pediatric Dosing Schedule (Ages 8-17)

• Initial dose: 25 mg at bedtime as a single daily dose 1
• Titration: Increase in 25 mg increments every 4-7 days based on tolerability 1
• Maximum for children ≤11 years: 200 mg/day 1
• Maximum for adolescents: 300 mg/day (adult maximum) 1
• Divided dosing: Total daily doses exceeding 50 mg should be split into two doses, with the larger dose given at bedtime 1
• Gender consideration: Therapeutic effect in female children may be achieved with lower doses 1

Critical Timeline Expectations

• Minimum trial duration: At least 8-10 weeks at maximum tolerated dose is required before declaring treatment failure 2
• Typical response: Therapeutic response typically occurs by week 6, with maximal benefit by weeks 10-12 or later 2
• Controlled trial duration: The FDA approval was based on trials ranging from 6-10 weeks in adults and pediatric populations 1, 3

Special Population Adjustments

• Elderly patients: Modify initial dose and subsequent titration due to decreased clearance of fluvoxamine 1
• Hepatic impairment: Modify initial dose and subsequent titration due to decreased clearance 1

Essential Safety Monitoring

• Suicidality surveillance: The FDA mandates close observation for clinical worsening, suicidality, and unusual behavioral changes, especially during initial treatment and after all dose changes, particularly in patients ≤24 years old 2, 1
• Early contact: Contact patients shortly after initiation to review adherence, current status, and emergence of adverse events 2
• Serotonin syndrome risk: Monitor for confusion, agitation, tremors, clonus, hyperreflexia, muscle rigidity, and autonomic instability, especially within 24-48 hours of dose changes or when combining with other serotonergic agents 4

Critical Drug Interactions

• Absolute contraindication: Never combine with MAOIs due to serotonin syndrome risk 4, 2
• CYP450 interactions: Fluvoxamine is a potent inhibitor of CYP1A2 and moderately inhibits CYP2C19, CYP2C9, CYP3A4, and CYP2D6, requiring caution with numerous concurrent medications 4, 2
• Specific caution: Exercise particular caution with alprazolam and triazolam, as fluvoxamine significantly increases their levels 2
• QT prolongation: Avoid combining with drugs that prolong QT interval 4

Discontinuation Protocol

• Taper gradually: Always taper over 1-2 weeks rather than stopping abruptly to minimize discontinuation syndrome 5, 1
• Discontinuation syndrome symptoms: Fluvoxamine is specifically associated with dizziness, fatigue, lethargy, myalgias, headaches, nausea, vomiting, diarrhea, insomnia, sensory disturbances, paresthesias, anxiety, and agitation 4, 5
• If intolerable symptoms occur: Resume the previously prescribed dose and decrease more gradually 1

Common Pitfalls to Avoid

• Starting too high: Starting at higher than recommended doses increases risk of deliberate self-harm and suicide-related events 2
• Inadequate trial duration: Declaring treatment failure before completing at least 8-10 weeks at maximum tolerated dose 2
• Abrupt discontinuation: Never stop fluvoxamine abruptly without tapering, as this dramatically increases risk of discontinuation syndrome 5
• Ignoring drug interactions: Fluvoxamine has greater potential for drug-drug interactions compared to other SSRIs like citalopram/escitalopram 4

Maintenance Therapy

• Long-term continuation: Although efficacy beyond 10 weeks has not been documented in controlled trials, OCD is a chronic condition and continuation is reasonable for responding patients 1
• Dose optimization: Maintain patients on the lowest effective dosage with periodic reassessment 1
• Relapse prevention: Maintenance therapy with fluvoxamine may reduce the likelihood of relapses in up to 67% of patients with OCD 3

Expected Efficacy

• Response rates: Clinical trials demonstrate response rates of 38-52% with fluvoxamine compared to 0-18% with placebo in OCD 3
• Comparative efficacy: Fluvoxamine has similar efficacy to clomipramine but appears better tolerated 3, 6
• Pediatric efficacy: In children and adolescents, efficacy is more modest, with response rates around 15% compared to 10% with placebo 7