QT Prolongation: Risks, Medications, and What You Need to Know
When your heart’s electrical cycle takes too long to reset, it’s called QT prolongation, a delay in the heart’s repolarization phase that can trigger life-threatening arrhythmias. Also known as long QT syndrome, it’s not always genetic—often, it’s caused by medications you’re already taking. This isn’t rare. Every year, dozens of commonly prescribed drugs—from antibiotics to antidepressants—have been flagged for this risk. You might not feel a thing until your heart skips or races dangerously. That’s why knowing which pills can cause it matters more than you think.
Many of the drugs linked to QT prolongation, a measurable delay on an ECG that increases risk of torsades de pointes are ones you’d never suspect. Antihistamines like cetirizine, certain antibiotics, antipsychotics like clozapine, and even some acid reducers can stretch the QT interval. It’s not about dosage alone—some people are genetically more sensitive. Combine those drugs with grapefruit juice, which slows how fast your body clears them, and the risk spikes. That’s why drug interactions, when two or more medications affect each other’s metabolism in dangerous ways are such a big deal. A simple mix you didn’t think twice about could be quietly stressing your heart.
It’s not just about the pills. People with kidney problems, low potassium, or existing heart conditions are at higher risk. Older adults on multiple meds? Especially vulnerable. And here’s the thing: doctors don’t always check for it unless you’re in the hospital. Most of the time, it’s picked up by accident during an ECG done for something else. That’s why reading your prescription labels matters. Look for warnings about heart rhythm changes, dizziness, or fainting. If you’ve ever passed out suddenly or felt your heart flutter out of nowhere, don’t brush it off. It could be your body’s warning.
This collection of posts doesn’t just list drugs that cause QT prolongation—it shows you how it connects to real-life situations. You’ll find articles on how common meds like cetirizine and clozapine affect your heart, how grapefruit juice can turn a safe dose into a dangerous one, and why switching to generics isn’t always harmless if your body’s sensitive. There’s also guidance on spotting early signs, what questions to ask your pharmacist, and how to avoid dangerous combinations. You won’t find fluff here—just clear, practical info that helps you protect your heart without panic.
QT Prolongation: Medications That Raise Arrhythmia Risk
Dec, 1 2025