What is the recommended protocol for switching from Lexapro (escitalopram) 10 mg daily to Prozac (fluoxetine)?

Switching from Lexapro 10 mg to Prozac: Protocol for Safe Transition

When switching from Lexapro (escitalopram) 10 mg daily to Prozac (fluoxetine), a gradual cross-taper approach is recommended to minimize withdrawal symptoms and ensure effective treatment continuation. 1

Rationale for Cross-Tapering

• Abrupt discontinuation of escitalopram can lead to withdrawal symptoms including dizziness, muscle tension, chills, confusion, amnesia, and crying 2
• Fluoxetine's very long half-life makes it uniquely suited for transitions from other SSRIs, as it provides a more gradual offset of serotonergic activity 3
• Higher doses and plasma concentrations of escitalopram are associated with greater risk of discontinuation syndrome, making gradual tapering essential 2

Recommended Cross-Taper Protocol

Week 1:

• Reduce Lexapro from 10 mg to 5 mg daily
• Start Prozac at 10 mg every other day 3

Week 2:

• Continue Lexapro at 5 mg daily
• Increase Prozac to 10 mg daily 3

Week 3:

• Discontinue Lexapro completely
• Continue Prozac at 10 mg daily
• After 1 week on Prozac alone, may increase to 20 mg daily if clinically indicated 3, 1

Important Considerations

• Monitor closely for both withdrawal symptoms and adverse effects during the transition period 1, 4
• Fluoxetine is more activating than escitalopram, which may benefit patients with fatigue but could worsen anxiety or insomnia 3
• Due to fluoxetine's very long half-life, side effects may not manifest for a few weeks after starting or increasing the dose 3
• Fluoxetine may inhibit metabolism of other medications through cytochrome P450 interactions - review concomitant medications 3

Potential Challenges and Solutions

• If withdrawal symptoms emerge during cross-tapering:

  • Consider slowing the taper of escitalopram further (e.g., using alternate-day dosing before complete discontinuation) 4, 5
  • Withdrawal symptoms are typically most pronounced early in the tapering process 5

• If activation symptoms (anxiety, insomnia) occur with fluoxetine:

  • Consider taking the dose in the morning rather than evening 3
  • Temporary use of a benzodiazepine may be considered for severe symptoms if no contraindications exist 3

Follow-up Recommendations

• Schedule follow-up within 1-2 weeks after completing the transition to monitor for adverse effects and treatment response 3
• Assess for both withdrawal symptoms from escitalopram and emergence of fluoxetine-specific side effects 1, 6
• Full therapeutic response to fluoxetine may take 4-8 weeks to develop 3

This cross-taper approach minimizes the risk of discontinuation syndrome while ensuring continuous antidepressant coverage during the transition from Lexapro to Prozac.