Medication combinations and physiology can compound risk
Polypharmacy is a central concern. SSRIs, methadone, antiarrhythmics, and other substances may overlap through cardiac rhythm effects, metabolism pathways, sedation, or changes in blood pressure. The FDA’s citalopram safety communication illustrates the broader clinical concern that some medicines can affect cardiac electrical activity.
Electrolyte disturbances—especially low potassium or magnesium—may add to rhythm risk. Vomiting, dehydration, poor intake, diarrhea, and withdrawal-related physical stress can all make electrolyte status less predictable. Hepatic impairment can further alter clearance and extend exposure in ways that are difficult to estimate outside clinical assessment.
When several risk factors overlap, their combined effect may be more important than any one factor considered alone.