CriticalSSRI (selective serotonin reuptake inhibitor)×Fourth-generation fluoroquinolone
Updated · Methodology
Mechanism
Moxifloxacin is named outright in both SSRI labels. Its own SmPC forbids concomitant use with other QT-prolonging drugs and quotes the measured QTc increase of about 6 ms. The citalopram SmPC lists ongoing treatment with any drug capable of prolonging the QT interval among its contraindications, with no exceptions.
Symptoms
QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.
Management
The pair sits in the citalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Moxifloxacin is the most cardiac of the fluoroquinolones, and respiratory infections have replacements outside that group. This pair is resolved on the antibiotic side.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Moxifloxacin tablet (Chartwell Rx, LLC) – Prescribing Information – QT prolongation warning (2016)– FDA Avelox label, Warnings and Precautions §5.7 – avoid with QT-prolonging drugs; DailyMed setid 656f582c-ecba-4ec8-9420-9562114d889b
- FDA: FDA Drug Safety Communication on citalopram QT prolongation (2012)
- AEMPS: Ficha técnica de Seropram 30 mg (citalopram) (2024)– AEMPS CIMA, nregistro 63564, revisión 01/2024, secciones 4.2, 4.3 y 4.4
- AEMPS: Ficha técnica de Moxifloxacino Sandoz 400 mg (2026)– AEMPS CIMA, nregistro 74573, revisión 03/2026, secciones 4.3 y 4.4