ModerateMacrolides×Calcineurin inhibitor (immunosuppressant)
Updated · Methodology
Mechanism
Additive QT prolongation (tacrolimus prolongs QT in hypomagnesaemia, common on calcineurin inhibitors).
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
For short azithromycin courses post-transplant: check magnesium and replete if needed. ECG before start if other QT-prolonging drugs are on board. Alternative antibiotics: a cephalosporin or doxycycline.
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: Prograf (tacrolimus) prescribing information (2013)– ; DailyMed setid 7f667de1-9dfa-4bd6-8ba0-15ee2d78873b
- AEMPS: Ficha técnica: Tacrolimus (nº registro 84607), sección 4.5 (2026)– AEMPS, CIMA, nº registro 84607, revisión 03/2026, sección 4.5