Celexa vs Lexapro
Celexa (citalopram) and Lexapro (escitalopram) are among the most closely related drugs in psychiatry — escitalopram is literally the active enantiomer of citalopram. Citalopram is a racemic mixture of two mirror-image molecules (S-citalopram and R-citalopram); escitalopram isolates only the therapeutically active S-form. Despite their molecular kinship, they differ in clinical practice in ways that matter: QTc prolongation risk, drug interactions, tolerability, and approved indications.
Quick Comparison
| Feature | Citalopram (Celexa) | Escitalopram (Lexapro) |
|---|---|---|
| Drug Class | SSRI (selective serotonin reuptake inhibitor) | SSRI (selective serotonin reuptake inhibitor) |
| Generic Name | Citalopram hydrobromide | Escitalopram oxalate |
| Brand Name | Celexa | Lexapro |
| Approved For | Major depressive disorder (MDD) | Major depressive disorder (MDD); generalized anxiety disorder (GAD) |
| Available as Generic | Yes — typically very inexpensive | Yes — inexpensive |
| Key Advantage | Lowest cost SSRI option; long clinical track record | Lower QTc risk; fewer drug interactions; broader FDA approval (includes GAD); generally cleaner tolerability profile |
| Main Drawback | FDA QTc warning limits maximum dose in elderly and cardiac patients; slightly more drug interactions; R-enantiomer may cause off-target effects | Slightly higher cost than citalopram (though still inexpensive as generic) |
How They're Similar
Citalopram and escitalopram share the same primary mechanism: they selectively block the serotonin transporter (SERT), preventing serotonin reuptake and increasing serotonergic activity in the synapse. Both are once-daily oral medications with long half-lives (~27–35 hours) that provide stable blood levels. Both require 2–4 weeks before meaningful antidepressant effects emerge, and full therapeutic benefit may take 6–8 weeks.
Both share the SSRI class side effect profile: nausea (especially early in treatment), insomnia or somnolence, sexual dysfunction (reduced libido, delayed orgasm), and the class-wide black box warning for increased suicidal ideation in younger patients. Neither has significant addiction potential, and both are available as inexpensive generics.
Key Differences
The enantiomer relationship: Citalopram is a racemic mixture — 50% S-citalopram (the therapeutically active form that blocks SERT) and 50% R-citalopram. The R-enantiomer does not contribute meaningfully to antidepressant efficacy but may interact with other receptors and contribute to side effects, including QTc prolongation. Escitalopram removes the R-enantiomer, delivering only the active S-form. This is why escitalopram is effective at half the milligram dose of citalopram in many patients.
QTc prolongation — a clinically significant safety difference: In 2011, the FDA issued a Drug Safety Communication for citalopram, warning that it causes dose-dependent QTc interval prolongation and capping the maximum recommended dose at 40 mg in most patients, and at 20 mg in patients over 60, those with hepatic impairment, or those taking CYP2C19 inhibitors. QTc prolongation increases the risk of potentially fatal arrhythmias (torsades de pointes). Escitalopram carries a lower QTc prolongation risk than citalopram — while not zero, the removal of the R-enantiomer significantly reduces this cardiac concern.
Drug interactions: Citalopram is metabolized primarily by CYP2C19, with contributions from CYP3A4 and CYP2D6. It also inhibits CYP2D6 to a minor degree. Escitalopram has a very similar metabolic profile but fewer clinically significant interactions overall — it is often cited as having one of the cleanest drug interaction profiles of any SSRI, along with sertraline. For patients on complex medication regimens, escitalopram's cleaner profile is often preferred.
FDA-approved indications: Citalopram is approved only for major depressive disorder. Escitalopram is approved for both MDD and generalized anxiety disorder (GAD). For patients with comorbid anxiety, escitalopram's on-label indication for GAD can be clinically and practically advantageous.
Tolerability: Head-to-head studies and meta-analyses (including Cipriani et al., 2018 Lancet network meta-analysis) consistently rank escitalopram among the best-tolerated SSRIs with high acceptability. Citalopram performs well but escitalopram consistently edges it out on tolerability metrics. The removal of the R-enantiomer's off-target effects appears to contribute to this modest but real difference.
Citalopram: Strengths & Weaknesses
Strengths: Very inexpensive generic, long clinical track record, simple once-daily dosing, effective antidepressant for MDD. Appropriate first-choice for patients with no cardiac risk factors, no need for GAD indication, and cost as a primary concern.
Weaknesses: FDA dose cap (especially in elderly) due to QTc risk limits its use in higher-dose situations. R-enantiomer contributes off-target effects. Narrower FDA indication (MDD only). Slightly higher drug interaction potential than escitalopram.
Escitalopram: Strengths & Weaknesses
Strengths: Lower QTc risk, fewer drug interactions, FDA-approved for GAD in addition to MDD, generally the highest-ranked SSRI for tolerability in network meta-analyses, no dose ceiling concerns in older adults from a cardiac perspective (standard monitoring still applies).
Weaknesses: Marginally higher cost than citalopram (though both are inexpensive generics). Some patients who do well on citalopram may not need to switch to escitalopram.
Which Is Right for You?
Only your prescriber can make this determination based on your full medical history. The following factors are considerations that typically guide clinical decision-making — they are not personal recommendations.
Escitalopram is generally preferred when starting a new SSRI, particularly in older adults, patients with cardiac conditions or QTc concerns, patients on multiple other medications, or when GAD is part of the clinical picture. Citalopram remains a reasonable choice for younger, otherwise healthy patients with MDD where cost is the primary concern and cardiac risk factors are absent.
If a patient is already doing well on citalopram with no side effects or cardiac concerns, there is typically no compelling reason to switch to escitalopram. The cleaner profile of escitalopram is most relevant when starting fresh or when citalopram is not being tolerated.
Frequently Asked Questions
Is Lexapro just a more expensive version of Celexa?
It is more accurate to say Lexapro is a refined version of Celexa. By isolating the active S-enantiomer, escitalopram achieves equivalent or superior antidepressant efficacy with lower QTc risk and fewer side effects. Both are now available as cheap generics, so the cost difference is minimal. The clinical differences are real, making escitalopram generally the preferred option for new starts.
What is QTc prolongation and why does it matter?
The QTc interval reflects the time it takes for the heart's lower chambers to electrically recover between beats. Prolongation of this interval increases the risk of a dangerous arrhythmia called torsades de pointes, which can degenerate into ventricular fibrillation and sudden death. Citalopram causes dose-dependent QTc prolongation, which led the FDA to issue maximum dose restrictions — particularly for older adults and those with heart conditions or on other QTc-prolonging drugs.
Can you switch from Celexa to Lexapro easily?
Yes. Switching from citalopram to escitalopram is one of the simpler SSRI transitions because they share the same mechanism and escitalopram is essentially the active component of citalopram. No washout period is required. Prescribers typically convert at approximately half the citalopram milligram dose for escitalopram, though the specific approach varies.
Are the sexual side effects different between the two?
Sexual dysfunction (reduced libido, delayed orgasm, erectile dysfunction) is a class effect of SSRIs and occurs with both citalopram and escitalopram. Head-to-head data do not consistently show one to be significantly better than the other on sexual side effects. Both carry rates in the 30–40% range reported in clinical trials. If sexual side effects are a primary concern, discuss alternatives such as bupropion or mirtazapine with your prescriber.
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⚠ This comparison is for informational purposes only. Never start, stop, or switch medications without guidance from a licensed healthcare provider. Individual responses to medication vary significantly.