Cross-Tapering from Citalopram 20 mg to Sertraline
For switching from citalopram 20 mg to sertraline, use a conservative cross-taper approach: gradually reduce citalopram by 50% while simultaneously starting sertraline at a low dose (25 mg), then complete the citalopram taper over 1-2 weeks before titrating sertraline to therapeutic levels. 1
Rationale for Conservative Cross-Taper Strategy
Both citalopram and sertraline are shorter-acting SSRIs with similar half-lives, making them suitable for a gradual cross-taper without requiring an extended washout period. 1 The key consideration is minimizing two primary risks:
Discontinuation syndrome risk: Both sertraline and citalopram (though to a lesser extent than paroxetine) are associated with discontinuation syndrome characterized by dizziness, fatigue, nausea, sensory disturbances, paresthesias, anxiety, and irritability. 1
Serotonin syndrome risk: When combining two serotonergic drugs, caution requires starting the second drug at a low dose, increasing slowly, and monitoring closely especially in the first 24-48 hours after dosage changes. 1
Specific Cross-Taper Protocol
Week 1:
- Reduce citalopram from 20 mg to 10 mg daily 1
- Start sertraline 25 mg daily (this is a subtherapeutic "test" dose to assess tolerability) 1
- Monitor closely for withdrawal symptoms or early serotonin syndrome signs (confusion, agitation, tremors, hyperreflexia, tachycardia, diaphoresis) 1
Week 2:
- Discontinue citalopram completely 2
- Continue sertraline 25 mg daily 2
- Continue monitoring for discontinuation symptoms from citalopram
Week 3-4:
- Increase sertraline to 50 mg daily (minimum therapeutic dose) 1
- Assess for tolerability and early response
Week 5-6 and beyond:
- Titrate sertraline in 50 mg increments at 1-2 week intervals as tolerated to achieve therapeutic response, up to maximum 200 mg daily 1
- The typical therapeutic range is 50-200 mg daily 1
Critical Safety Considerations
Avoid alternate-day dosing during the taper. Recent evidence demonstrates that dosing antidepressants every other day when tapering causes pronounced increases in receptor occupancy variation, likely increasing withdrawal symptom risk and cannot be recommended. 3 This applies to both the citalopram taper and sertraline titration phases.
Monitor for QT prolongation. Citalopram can cause QT prolongation at doses exceeding 40 mg daily, though this is not a concern at the 20 mg starting dose. 1 However, if the patient has baseline QT prolongation or is on other QT-prolonging medications, obtain baseline and follow-up ECGs.
Drug interaction profile favors this switch. Citalopram/escitalopram have the least effect on CYP450 isoenzymes compared with other SSRIs, and sertraline has less effect on metabolism of other medications compared to other SSRIs. 1 This makes the cross-taper pharmacologically safer.
Monitoring During Cross-Taper
First 48 hours after each dose change are critical for detecting early serotonin syndrome. 1 Specifically assess for:
- Mental status changes (confusion, agitation, anxiety)
- Neuromuscular hyperactivity (tremors, clonus, hyperreflexia, muscle rigidity)
- Autonomic hyperactivity (hypertension, tachycardia, diaphoresis, vomiting, diarrhea)
Throughout the taper, monitor for discontinuation syndrome symptoms, particularly during weeks 1-3 when citalopram is being reduced and eliminated. 1
Common Pitfalls to Avoid
Do not use direct substitution (stopping citalopram abruptly and starting sertraline the next day). This increases risk of both discontinuation syndrome and potential serotonin-related adverse effects. 2
Do not rush the sertraline titration. Starting sertraline at higher doses (≥50 mg) during the cross-taper increases serotonin syndrome risk. 1 The initial 25 mg dose serves as a test dose since an initial adverse effect of SSRIs can be anxiety or agitation. 1
Do not extend the washout period unnecessarily. Unlike switching from fluoxetine (which has a long half-life requiring 3-4 week intervals) or switching to/from MAOIs (which requires 2-week washouts), the shorter half-lives of citalopram and sertraline allow for a 1-2 week cross-taper without extended drug-free periods. 1