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

When your heart’s electrical cycle gets out of sync, it can lead to something called QT prolongation, a delay in the heart’s repolarization phase that increases the risk of dangerous irregular heartbeats. Also known as long QT syndrome, it’s not always genetic—many cases are triggered by everyday medications. This isn’t just a lab result; it’s a real, measurable risk that can lead to torsades de pointes, a life-threatening type of irregular heartbeat that can cause fainting, seizures, or sudden cardiac arrest. You might not feel anything until it’s too late, which is why knowing which drugs can cause it matters more than you think.

Many common prescriptions and even some over-the-counter meds can stretch out your QT interval. Antidepressants like mirtazapine, a drug used for depression and anxiety that affects serotonin and norepinephrine, and duloxetine, an SNRI often prescribed for nerve pain and depression, have been linked to QT changes in sensitive individuals. Even antibiotics like Cefdinir (Omnicef), a cephalosporin used for bacterial infections, and antifungals like fluconazole, a common treatment for fungal infections including Candida, can play a role. It’s not about avoiding these drugs—it’s about understanding your personal risk. If you’re on multiple meds, have a history of heart issues, or take diuretics like amiloride, a potassium-sparing diuretic that can alter electrolyte balance, your risk goes up.

Electrolyte imbalances—low potassium, low magnesium—are big triggers. That’s why people on diuretics, or those with eating disorders or chronic vomiting, need extra monitoring. It’s also why some people handle a drug fine for months, then suddenly develop QT prolongation after a bout of illness or dehydration. The key isn’t fear—it’s awareness. If you’ve been told your QT is prolonged, or if you’ve had unexplained dizziness or fainting, talk to your doctor about your full medication list. You don’t have to stop your treatment. You just need to know what to watch for and when to get checked.

What you’ll find below are real, practical guides from people who’ve dealt with these risks firsthand. From how mirtazapine affects your heart rhythm to why fluconazole might be safer than you think, these posts cut through the noise. You’ll see exactly which meds carry the highest risk, how doctors test for QT prolongation, and what steps you can take to protect yourself—without giving up the treatment you need.