My severe OCD is worsening despite lamotrigine 200 mg daily and fluvoxamine ER 100 mg twice daily; should I increase the fluvoxamine dose or adjust my treatment?

Increase Fluvoxamine Dose to 150 mg Twice Daily (300 mg Total)

You should increase fluvoxamine ER to 150 mg twice daily (300 mg total daily dose), as you are currently on only 200 mg daily—well below the maximum recommended dose of 300 mg/day for OCD—and guidelines emphasize that higher doses are required for OCD than other conditions, with at least 8-10 weeks at maximum tolerated dose needed before declaring treatment failure. 1

Rationale for Dose Escalation

• The FDA-approved maximum dose for fluvoxamine in adult OCD is 300 mg per day, typically given as 150 mg twice daily when the total exceeds 100 mg. 2

• OCD specifically requires higher SSRI doses than depression or other anxiety disorders, and therapeutic response typically occurs by week 6, with maximal benefit by weeks 10-12 or later. 1

• Your current dose of 200 mg daily represents only 67% of the maximum recommended dose, leaving substantial room for optimization before considering treatment failure or switching strategies. 1, 2

• Fluvoxamine demonstrates response rates of 38-52% in OCD at doses of 100-300 mg/day, compared to 0-18% with placebo, and the drug has proven efficacy as first-line treatment for OCD. 3

Dose Titration Protocol

• Increase by 50 mg increments every 4-7 days as tolerated until reaching 300 mg/day (150 mg twice daily, with the larger dose at bedtime if doses are unequal). 2

• Specifically for your case: increase from 100 mg twice daily (200 mg total) to 150 mg twice daily (300 mg total) over 1-2 weeks. 2

• Allow a full 8-10 weeks at the maximum tolerated dose (ideally 300 mg/day) before declaring treatment failure, as this is the minimum duration needed to assess full therapeutic response in OCD. 1

Role of Lamotrigine

• Lamotrigine 200 mg daily may provide glutamatergic augmentation benefit for treatment-resistant OCD, with one case report showing significant improvement when added to clomipramine at 150 mg/day lamotrigine. 4

• Continue lamotrigine 200 mg daily while optimizing fluvoxamine, as the combination addresses both serotonergic and glutamatergic mechanisms without significant drug-drug interaction concerns. 4

• Lamotrigine augmentation should be maintained during fluvoxamine dose escalation, as the glutamatergic mechanism may provide synergistic benefit. 4

Critical Safety Monitoring

• Monitor closely for serotonin syndrome within 24-48 hours after each dose increase: confusion, agitation, tremor, clonus, hyperreflexia, muscle rigidity, and autonomic instability (fever, tachycardia, blood pressure changes). 1

• Assess for suicidality at every contact during the first 1-2 months after dose adjustments, particularly in patients ≤24 years old, as this period carries the highest risk for treatment-emergent suicidal ideation. 1

• Contact the patient within 1 week of each dose increase to review adherence, tolerability, and emergence of adverse events. 1

Drug Interaction Considerations

• Fluvoxamine is a potent inhibitor of CYP1A2 and moderately inhibits CYP2C19, CYP2C9, CYP3A4, and CYP2D6, requiring careful review of all concurrent medications. 1

• Lamotrigine is primarily metabolized by glucuronidation (not CYP450 enzymes), so no significant pharmacokinetic interaction is expected between fluvoxamine and lamotrigine. 4

• Avoid combining fluvoxamine with MAOIs (absolute contraindication), other serotonergic agents, or QT-prolonging medications. 1

Common Pitfalls to Avoid

• Do not switch medications or add augmentation agents before completing an adequate trial of fluvoxamine at 300 mg/day for 8-10 weeks, as premature switching leads to missed therapeutic opportunities. 1

• Do not abruptly discontinue fluvoxamine if switching becomes necessary; taper gradually over 1-2 weeks to minimize discontinuation syndrome (dizziness, fatigue, myalgias, headaches, nausea, insomnia, sensory disturbances, anxiety, agitation). 1

• Do not increase doses more rapidly than every 4-7 days, as faster titration increases the risk of adverse effects and behavioral activation without improving efficacy. 2

Expected Timeline and Monitoring

• Week 1-2: Increase to 250 mg daily (e.g., 100 mg AM, 150 mg PM), monitor for tolerability. 2

• Week 2-3: Increase to 300 mg daily (150 mg twice daily), monitor for adverse effects. 2

• Weeks 3-12: Maintain 300 mg daily and reassess OCD symptoms at weeks 6,8, and 10-12 using standardized scales (Y-BOCS). 1

• If no response after 10-12 weeks at 300 mg/day, consider augmentation strategies (e.g., antipsychotics) or switching to clomipramine. 1, 3

Tolerability Profile

• Most common adverse events with fluvoxamine include nausea (>10%), somnolence, asthenia, headache, dry mouth, and insomnia, with most events being mild to moderate. 3

• Fluvoxamine is associated with a low risk of sexual dysfunction and withdrawal syndrome compared to other SSRIs, and fewer anticholinergic or cardiovascular events than tricyclic antidepressants. 3

• Nausea typically emerges early in treatment and often resolves with continued therapy; taking doses with food may improve tolerability. 3