Causality assessment · Causality: well established

Citalopram and QT prolongation: is the FAERS signal real?

n=1,712 co-reports · PRR 7.7 · ROR 7.7

Citalopram side-effect profile All assessments See in the full list

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Causality: well established

Citalopram ↔ QT prolongation

n=1,712 co-reports · PRR 7.7 · ROR 7.7

Citalopram produces a dose-dependent prolongation of the QT interval on the electrocardiogram, which in susceptible patients can progress to the dangerous ventricular arrhythmia torsades de pointes. The effect was confirmed by dedicated “thorough QT” studies, and in 2011–2012 the FDA issued a safety communication restricting the maximum dose (to 40 mg/day for adults, 20 mg/day for those over 60, and lower in hepatic impairment or with CYP2C19 inhibitors), with a similar action from European regulators. Notably, the closely related SSRI escitalopram carries a smaller effect, which is part of why citalopram is treated as the more QT-active of the two. This is a well-quantified, mechanism-based cardiac effect — not a reporting artifact — established through dedicated ECG trials rather than post-marketing impression.

Regulatory basis: FDA drug-safety communication on citalopram QT prolongation and maximum-dose restriction (2011–2012); EMA equivalent. Thorough-QT-study data.

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	QT change appears with exposure and resolves after discontinuation
Strength	partial	PRR 8, moderate — a small ECG effect rather than a large event rate
Consistency	met	Reproduced in dedicated QT studies and confirmed by regulators
Specificity	partial	Shared to a lesser degree with other serotonergic and QT-active drugs
Biological gradient	met	Clearly dose-related — the basis for the maximum-dose restriction
Plausibility	met	hERG-channel blockade prolonging cardiac repolarization — a defined mechanism
Coherence	met	Coheres with the broader QT-prolongation pharmacology
Experiment	met	Dedicated thorough-QT trials and the dose restriction are direct experimental evidence
Analogy	met	Analogous to other QT-prolonging drugs (e.g. methadone, ondansetron)

This page's own qualitative read, not an automated/citation-gated assessment.

✗ No ClinicalTrials.gov results-posting trial in the top search hits for citalopram captured QT prolongation as a tracked adverse-event term. QT effects are measured with dedicated ECG endpoints rather than coded as adverse events in routine outcome trials, so the evidence base is the thorough-QT studies and the regulatory dose restriction, not trial AE tables.