MajorSulfonamide-trimethoprim combination×Angiotensin II receptor blockers (sartans)
Updated · Methodology
Mechanism
Trimethoprim blocks sodium channels via an amiloride-like mechanism, additively with an ARB (losartan) causing hyperkalaemia. In older patients, sudden death risk rises.
Symptoms
Muscle weakness, paraesthesia, slowed pulse, arrhythmias. ECG: peaked T waves, widened QRS. Severe cases progress to cardiac arrest.
Management
During co-trimoxazole therapy, check potassium 3 days after start. In older patients and chronic kidney disease, prefer alternative antibiotics (nitrofurantoin, fosfomycin).
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 →