What dose of bupropion (Wellbutrin) is equivalent to 20 mg of escitalopram (Lexapro)?

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Last updated: October 28, 2026 • View editorial policy

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There Is No Direct Dose Equivalence Between Lexapro and Wellbutrin

These medications work through completely different mechanisms and cannot be directly converted or considered equivalent on a milligram-per-milligram basis. Escitalopram (Lexapro) is a selective serotonin reuptake inhibitor (SSRI), while bupropion (Wellbutrin) is a norepinephrine-dopamine reuptake inhibitor—they are fundamentally different drug classes that cannot be equated by dose 1.

Why This Question Has No Simple Answer

The concept of "equivalence" between these medications is flawed because:

  • Different mechanisms of action: Lexapro affects serotonin; Wellbutrin affects norepinephrine and dopamine
  • Different side effect profiles: Wellbutrin has lower sexual dysfunction rates but higher seizure risk 1
  • Different clinical applications: They're chosen based on patient-specific factors, not interchangeable doses

What the Evidence Actually Shows

Comparative Efficacy Research

The most relevant study comparing these medications found that escitalopram 10-20 mg daily showed similar efficacy to bupropion XL 300 mg daily in treating major depressive disorder 2. However, this does not mean 20 mg of escitalopram "equals" 300 mg of bupropion—it means both were effective at these therapeutic doses.

Dose Equivalence Data

One systematic analysis of antidepressant dose equivalence calculated that fluoxetine 40 mg/day was equivalent to:

  • Escitalopram 18.0 mg/day
  • Bupropion 348.5 mg/day 3

Using this indirect comparison, 20 mg escitalopram would roughly correspond to bupropion 387 mg/day. However, this calculation is purely theoretical and should not guide clinical switching decisions.

Clinical Approach to Switching

When switching from escitalopram 20 mg to bupropion, start bupropion at its standard therapeutic dose (150-300 mg XL daily), not based on mathematical conversion 4.

Practical Switching Strategy:

  • Cross-taper approach: Begin bupropion XL 150 mg daily while maintaining escitalopram
  • Week 1-2: Continue both medications
  • Week 2-4: Gradually taper escitalopram while increasing bupropion to 300 mg if needed
  • Monitor closely: Assess within 1-2 weeks for worsening depression or suicidality 1

Key Safety Considerations:

  • Bupropion has significantly higher overdose toxicity than SSRIs, with increased risk of seizures (27.0% vs 8.5%), death, and serious outcomes 5
  • Sexual dysfunction is markedly lower with bupropion compared to escitalopram 6
  • Both require 14-day washout when switching to/from MAOIs 4

Common Pitfall to Avoid

Do not attempt mathematical dose conversion between these medications. The American College of Physicians guideline emphasizes that second-generation antidepressants should be selected based on adverse effect profiles, cost, and patient preferences—not dose equivalence, because efficacy does not differ significantly between agents 1. The choice to switch should be based on inadequate response after 6-8 weeks, tolerability issues, or patient-specific factors, not on finding an "equivalent" dose.

References

Related Questions

How should I switch from escitalopram (Lexapro) 10 mg to bupropion (Wellbutrin)?
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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.