What is the recommended dose of Prozac (fluoxetine) for someone with severe Obsessive-Compulsive Disorder (OCD)?

Fluoxetine Dosing for Severe OCD

For severe OCD, fluoxetine (Prozac) should be initiated at 20 mg/day and titrated up to 60-80 mg/day as needed, with the maximum recommended dose being 80 mg/day. 1, 2

Initial Dosing and Titration

• Start with 20 mg/day administered in the morning 1
• After several weeks, if insufficient clinical improvement is observed, consider dose increases 1
• For severe OCD, most patients will require higher doses in the 40-80 mg range 2
• Doses can be administered once daily (morning) or twice daily (morning and noon) if needed 1

Target Dosing for Severe OCD

• Target dose range: 20-60 mg/day 2
• Maximum dose: 80 mg/day 1
• Higher doses (60-80 mg/day) are often needed for severe OCD cases 1, 3

Timing and Response Expectations

• Full therapeutic effect may be delayed until 5 weeks of treatment or longer 1
• Efficacy should not be evaluated before 8 weeks to allow for onset of therapeutic effects 4
• Some patients may require up to 16 weeks to show significant improvement 5

Monitoring and Side Effects

• Common side effects include insomnia, headache, and diminished libido 4
• Monitor for suicidal ideation, particularly in the first months of treatment and following dose adjustments 2
• Watch for behavioral activation/agitation, especially in early treatment and after dose changes 2

Duration of Treatment

• Continue treatment for 12-24 months after remission 2
• Long-term maintenance therapy is often necessary as OCD is a chronic condition 1
• Efficacy can be maintained for extended periods (up to 3 years in some studies) 4

Special Considerations

• Lower or less frequent dosing should be used in patients with:
  • Hepatic impairment
  • Elderly patients
  • Concurrent disease
  • Multiple concomitant medications 1
• Dosage adjustments for renal impairment are not routinely necessary 1

Treatment-Resistant Cases

• If fluoxetine is ineffective after an adequate trial (8-12 weeks at maximum tolerated dose), consider:
  1. Switching to another SSRI
  2. Switching to clomipramine
  3. Augmentation strategies (antipsychotics, glutamatergic agents)
  4. Adding CBT with Exposure and Response Prevention (ERP) 2

Remember that while medication is important, combining fluoxetine with Cognitive Behavioral Therapy with Exposure and Response Prevention (CBT-ERP) provides the most effective treatment for OCD, with larger effect sizes than medication alone 2.