QT Prolongation: Risks, Medications, and What You Need to Know

When your heart’s electrical cycle takes too long to reset between beats, it’s called QT prolongation, a delay in the heart’s repolarization phase that can trigger life-threatening irregular heartbeats. Also known as long QT syndrome, it’s not always genetic—often, it’s caused by medications you’re already taking. This isn’t just a lab value; it’s a real, measurable risk that can lead to torsades de pointes, a specific type of dangerous ventricular arrhythmia that can cause fainting, seizures, or sudden death. You might not feel anything until it’s too late, which is why knowing what triggers it matters more than ever.

Many common drugs can cause QT prolongation, especially those used in mental health and chronic conditions. Antipsychotics, like clozapine and loxapine, are among the strongest offenders. Even drugs you think are safe—like certain antibiotics, antidepressants, or stomach medications—can add up. If you’re on more than one of these, your risk doesn’t just add up—it multiplies. The same goes for people with low potassium, low magnesium, or existing heart conditions. It’s not just about the drug; it’s about your body’s environment when you take it.

Some medications don’t cause QT prolongation on their own but become risky when mixed. For example, combining a drug that affects liver enzymes—like charcoal-grilled meat triggering CYP1A2 changes—with a QT-prolonging agent can push your heart into danger zone. Even something as simple as skipping a meal or getting dehydrated can drop your electrolytes enough to tip the balance. This is why doctors check your ECG before starting certain meds, and why you need to speak up if you’ve had unexplained fainting spells or family history of sudden cardiac death.

What you’ll find here isn’t theory. These are real cases, real drugs, and real advice from people who’ve been there. We’ve pulled together posts that break down which antipsychotics carry the highest risk, how common drugs like azathioprine or amitriptyline interact with heart rhythm, and what you can do to reduce your exposure. You’ll learn how to talk to your doctor about testing, what symptoms to watch for, and how to avoid dangerous combinations—without needing a medical degree.