No, Taking Two SSRIs Concurrently Is Not Appropriate
Combining two SSRIs such as Zoloft (sertraline) and Lexapro (escitalopram) is not recommended due to the significant risk of serotonin syndrome, lack of therapeutic benefit, and absence of supporting evidence.
Why This Practice Should Be Avoided
Risk of Serotonin Syndrome
The primary concern with combining two SSRIs is serotonin syndrome, a potentially life-threatening condition caused by excessive serotonergic activity 1. This syndrome can develop within 24-48 hours of combining serotonergic medications and manifests as:
- Mental status changes: confusion, agitation, anxiety
- Neuromuscular hyperactivity: tremors, clonus, hyperreflexia, muscle rigidity
- Autonomic hyperactivity: hypertension, tachycardia, arrhythmias, diaphoresis, vomiting
Advanced cases can progress to fever, seizures, arrhythmias, unconsciousness, and death 1. The FDA drug label for Lexapro explicitly warns about serotonin syndrome risk when combining with other serotonergic drugs 2.
Lack of Evidence for Dual SSRI Therapy
There is no clinical evidence supporting the use of two SSRIs simultaneously. Guidelines emphasize caution when combining any two non-MAOI serotonergic drugs, including SSRIs 1. The American College of Physicians recommends selecting a single second-generation antidepressant based on adverse effect profiles, cost, and patient preferences—not combining them 3.
What to Do Instead
When a patient doesn't respond adequately to a single SSRI:
Optimize the current SSRI dose within the therapeutic range before switching 1
Switch to a different single antidepressant if inadequate response after 6-8 weeks 3
Consider augmentation strategies that have evidence:
- Add psychotherapy (CBT) to the SSRI 1
- Add a medication from a different class (not another SSRI)
If switching between SSRIs, ensure proper washout period to avoid overlap 2
Important Caveats
Drug Interaction Concerns
Even if serotonin syndrome doesn't occur, combining sertraline and escitalopram creates unnecessary pharmacokinetic complexity. While escitalopram has relatively low CYP450 interaction potential 1, sertraline can interact with CYP2D6 substrates 1. This combination offers no therapeutic advantage while increasing monitoring burden.
The FDA Label Is Clear
The Lexapro prescribing information explicitly states: "Since escitalopram is the active isomer of racemic citalopram (Celexa), the two agents should not be coadministered" 2. While this specifically addresses escitalopram and citalopram, the principle extends to all SSRI combinations—there's no rationale for using two drugs targeting the same mechanism.
When Combination Therapy Makes Sense
The evidence does support combining an SSRI with CBT, which shows superior outcomes compared to either treatment alone 1. This is the appropriate "combination" approach for treatment-resistant cases.
Clinical Bottom Line
Switch, don't stack. If sertraline isn't working, transition to escitalopram (or vice versa) with appropriate tapering, or add evidence-based augmentation like psychotherapy. Never run two SSRIs concurrently—the risk-benefit ratio is unacceptable, with documented mortality risk from serotonin syndrome and zero evidence of benefit 1, 2.