How to switch from Lexapro (escitalopram) 10mg to Prozac (fluoxetine)?

Switching from Lexapro (Escitalopram) 10mg to Prozac (Fluoxetine)

Use a cross-taper approach over 1-2 weeks: reduce escitalopram to 5mg daily while starting fluoxetine 10-20mg daily for one week, then discontinue escitalopram completely while continuing fluoxetine. 1, 2

Cross-Taper Protocol

The recommended switching strategy involves gradual cross-tapering rather than abrupt discontinuation or conservative washout periods. 3, 4

Week 1:

• Reduce escitalopram from 10mg to 5mg (50% reduction) 2
• Simultaneously start fluoxetine 10-20mg daily 1, 4
• This overlap period maintains antidepressant coverage while minimizing withdrawal risk 1

Week 2:

• Discontinue escitalopram completely 2
• Continue fluoxetine at the same dose 2
• Fluoxetine can be titrated upward after 4-6 weeks if needed for optimal response 4

Critical Safety Monitoring

Monitor intensively for serotonin syndrome during the overlap period, especially in the first 24-48 hours. 1, 2 Key symptoms include:

• Tremor, neuromuscular rigidity, hyperreflexia 1
• Agitation, confusion, mental status changes 1
• Tachycardia, hyperthermia, diaphoresis 1
• Diarrhea and sweating 2

The cross-taper approach significantly reduces discontinuation syndrome risk compared to abrupt cessation. 2 Watch for escitalopram withdrawal symptoms including:

• Dizziness, vertigo, sensory disturbances 1
• Irritability, anxiety, headache 1
• Nausea, fatigue, insomnia 1

Rationale for This Approach

Direct or rapid cross-taper switching is well-tolerated between SSRIs and does not require washout periods. 3, 4 The conservative approach with prolonged washout is unnecessary when switching between non-MAOI antidepressants and risks treatment gaps with potential symptom exacerbation. 3

Escitalopram has minimal effect on CYP450 enzymes, reducing drug interaction concerns during the overlap. 1 Fluoxetine's long half-life (4-6 days for fluoxetine, 4-16 days for its active metabolite norfluoxetine) provides built-in protection against discontinuation symptoms once established. 3

Follow-Up Schedule

Contact the patient during weeks 1-2 to assess tolerability and adherence. 2 Schedule a follow-up visit after completing the switch (week 3-4) to evaluate:

• Therapeutic response 2
• Adverse effects 2
• Need for dose adjustment 2

Fluoxetine typically requires 4-8 weeks at therapeutic doses before assessing full efficacy. 5, 6

Common Pitfalls to Avoid

Never abruptly discontinue escitalopram - this significantly increases discontinuation syndrome risk. 2

Do not use conservative washout periods between these SSRIs - this unnecessarily prolongs the switch and risks symptom recurrence. 3, 4

Monitor adherence closely - patients may discontinue one medication without starting the other, leading to relapse. 2

Avoid combining with MAOIs or other serotonergic agents beyond the planned cross-taper period. 2

Special Considerations

For elderly patients or those with hepatic impairment, consider:

• More gradual cross-taper over 2-3 weeks 2
• Lower starting dose of fluoxetine (10mg rather than 20mg) 2
• More frequent monitoring 2

The switch from escitalopram to fluoxetine is appropriate when seeking different pharmacologic properties within the SSRI class, such as fluoxetine's longer half-life or different side effect profile. 7, 6