Major
Fluconazole × Haloperidol
Antifungals, triazole derivatives×First-generation antipsychotics. Butyrophenone derivatives
Mechanism
Dual mechanism. Fluconazole prolongs QT and blocks CYP3A4 and CYP2D6 – haloperidol metabolic routes. Haloperidol plasma levels rise; QT effects add up.
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
Avoid the combination. Alternative antifungals: terbinafine or echinocandins. Alternative antipsychotics with minimal QT effect: olanzapine or aripiprazole.
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.