SSRI Dose Equivalency: Lexapro to Zoloft
Based on the best available evidence from randomized controlled trials, Lexapro (escitalopram) 10 mg is approximately equivalent to Zoloft (sertraline) 50 mg. 1
Evidence-Based Dose Conversion
The most rigorous method for determining antidepressant dose equivalency comes from a systematic analysis of 83 randomized, double-blind, flexible-dose trials involving 14,131 participants 1. This study calculated weighted mean dose ratios from head-to-head comparisons:
- Escitalopram 10 mg = Sertraline 54.7 mg (calculated from the study's fluoxetine 40 mg equivalents: escitalopram 18 mg and sertraline 98.5 mg) 1
- Practical conversion: Lexapro 10 mg ≈ Zoloft 50 mg
This conversion is based on actual prescribing patterns in clinical trials where doses were adjusted flexibly to achieve optimal therapeutic response, making it more clinically relevant than arbitrary consensus methods 1.
Dosing Context from Guidelines
Both medications fall within standard therapeutic ranges for depression and anxiety disorders 2:
The American Family Physician guidelines note that sertraline is well tolerated and has less effect on metabolism of other medications compared with other SSRIs, while escitalopram/citalopram may have the least effect on CYP450 isoenzymes and lower propensity for drug interactions 2.
Clinical Considerations When Switching
Direct switch approach: When converting between these SSRIs, you can typically stop one and start the other the next day at the equivalent dose, as neither requires extensive washout periods 3.
Pharmacokinetic differences to consider:
- Escitalopram has a half-life of 27-33 hours with steady-state achieved in 7-10 days 3
- Both medications can be titrated at 1-2 week intervals 2
- Sertraline has been associated with discontinuation syndrome, though less prominently than paroxetine 2
Monitoring: Assess response using standardized symptom rating scales at regular intervals, typically every 1-2 weeks during the initial titration phase 2.