QT Prolongation: What It Is, Why It Matters, and How Medications Can Cause It

When your heart’s electrical system takes too long to reset between beats, it’s called QT prolongation, a measurable delay in the heart’s repolarization phase that can lead to dangerous irregular rhythms. Also known as long QT syndrome, it’s not always genetic—often, it’s triggered by everyday medications, especially when combined with other risk factors. This isn’t just a lab number; it’s a silent warning sign that can lead to torsades de pointes, a type of ventricular arrhythmia that can cause sudden cardiac arrest.

Many drugs you might be taking—antibiotics like azithromycin, antifungals like fluconazole, antidepressants like citalopram, and even some anti-nausea meds—can stretch out the QT interval. It’s not about taking one pill alone; it’s about how they interact with your body’s chemistry. Low potassium, low magnesium, or dehydration make this risk worse. Even people with no heart history can develop this if they’re on multiple medications or have kidney issues that affect how drugs are cleared. Drug interactions, the unintended effects when two or more medications affect each other’s behavior in the body are a major driver here. And electrolyte imbalance, a disruption in the levels of minerals like potassium and magnesium that control heart rhythm is often the missing piece that turns a slow QT into a medical emergency.

Doctors don’t just guess—they use ECGs to measure the QT interval and check for signs of trouble. But you don’t need to wait for a hospital visit. If you’re on any new medication and start feeling dizzy, faint, or notice your heart skipping or pounding hard, speak up. Many of the posts here focus on real-world medication risks: how generic drugs can vary in quality, how drug interactions sneak up on you, and why some prescriptions need extra monitoring. You’ll find clear advice on spotting red flags in your meds, understanding what your pharmacist should be watching for, and how to protect yourself from hidden dangers that don’t show up on the label.