citalopram

General Information

Citalopram is an SSRI used for major depressive and anxiety disorders in patients with serious mental illness, notable for relatively low drug interactions but dose-dependent QTc prolongation.

Clinical response often begins within 2–4 weeks, but an adequate trial frequently requires 6–8 weeks at a therapeutic dose; plan for gradual tapering to reduce discontinuation symptoms.

The citalopram compare view, citalopram evidence feed, and citalopram print page can be used together for shared decision-making; the bipolar disorder hub summarizes considerations when balancing antidepressant benefits against mania switch risk in mood disorders.

Sexual dysfunction and sleep disruption are common SSRI-class issues; documenting baseline symptoms helps distinguish medication side effects from the underlying mood/anxiety disorder.

Dose limited to 40 mg/day (20 mg/day in older adults/hepatic impairment/CYP2C19 inhibitors) due to QTc prolongation; consider escitalopram for lower QT risk.

Mechanism of Action

Refer to the Glossary entry on Neurotransmitters for background on receptor systems involved in serious mental illness.

Selectively inhibits serotonin reuptake, increasing synaptic serotonin; little affinity for other receptors.

• Selective serotonin transporter inhibitor.

Metabolism and Pharmacokinetics

• Metabolized via CYP2C19 and CYP3A4 (minor CYP2D6); half-life ~35 h; steady state in 1 week.
• Hepatic impairment can increase exposure; dosing caps and slower titration are used to reduce QTc risk and adverse effects.

Dosing and Administration

• Typical start is 20 mg once daily; increase to 40 mg/day after ≥4 weeks if needed (limit to 20 mg/day for ≥60 years, hepatic impairment, CYP2C19 inhibitors).
• Gradual tapering can reduce discontinuation symptoms.
• When discontinuation symptoms occur despite tapering, extending the taper interval (smaller steps over longer periods) is often better tolerated than abrupt pauses or rapid reductions.

Monitoring & Labs

• QTc monitoring when cardiac risk is present or when combining multiple QT-active medications; recheck ECG after dose changes when indicated.
• Sodium in older adults or patients on diuretics if symptoms suggest hyponatremia.
• Bleeding/bruising risk when combined with NSAIDs, antiplatelets, or anticoagulants; reinforce early symptom reporting.
• Mood elevation or agitation in bipolar-spectrum illness; coordinate prevention plans via the bipolar disorder hub.

Citalopram is relatively low-interaction, but dose-dependent QT risk is a key differentiator from other SSRIs; keep documentation clear when higher doses are used or complex polypharmacy is present, or comorbidity.

Adverse Effects

Interactions

• CYP2C19 inhibitors (omeprazole, fluconazole) increase levels—limit dose to 20 mg/day and monitor QTc.
• Label contraindicates concomitant use with MAOIs/linezolid due to serotonin syndrome risk.
• Additive QTc risk with antipsychotics (ziprasidone, haloperidol)—monitor ECG.
• Use caution with other serotonergic agents (triptans, tramadol, SNRIs, linezolid, St. John’s wort) that can raise serotonin syndrome risk.

Other Useful Information

• Counseling often covers serotonin syndrome warning signs and when to seek care for palpitations, syncope, or persistent nausea.
• Consider escitalopram (S-enantiomer) for patients needing higher potency with similar tolerability.
• For patients with elevated QT risk, documentation often includes a monitoring plan (baseline ECG, electrolytes, follow-up after dose changes), and layering multiple QT-active medications is generally avoided when alternatives exist.
• When switching antidepressants, the QT plan is often kept explicit (dose caps, ECG timing, and electrolyte checks), and overlapping multiple QT- and serotonergic-active medications is generally avoided when alternatives exist.

References

1. Citalopram prescribing information — DailyMed (2025)
2. FDA Citalopram QT 2012
3. CANMAT 2016 Clinical Guidelines for the Management of Adults with Major Depressive Disorder — Canadian Journal of Psychiatry (2016)
4. CANMAT 2024 Clinical Guidelines for Major Depressive Disorder — Canadian Journal of Psychiatry (2024)
5. Comparative efficacy and acceptability of 21 antidepressant drugs for major depressive disorder — The Lancet (2018)Meta-analysisdepressionefficacy