Antipsychotics and QT-Prolonging Drugs: What You Need to Know About Heart Risks

When you’re taking an antipsychotic for schizophrenia, bipolar disorder, or severe depression, your mind might feel more stable-but your heart could be under silent stress. Many of these medications, while effective for mental health, can slow down the electrical recovery of your heart muscle. When combined with other common drugs-like certain antibiotics, anti-nausea meds, or even some antidepressants-that same effect adds up. The result? A dangerous stretch in your heart’s electrical cycle called QT prolongation. And in rare but deadly cases, it can trigger a life-threatening rhythm called torsades de pointes.

What QT Prolongation Really Means

Your heart beats because of electrical signals. After each beat, it needs time to reset before the next one. That reset phase is measured as the QT interval on an ECG. If it lasts too long-over 450 milliseconds in men, 460 in women-it creates a window where the heart can misfire. This isn’t just a lab number. It’s a real, measurable risk for sudden cardiac arrest.

The problem starts with how antipsychotics work. Many block a specific potassium channel in heart cells called hERG. When this channel is blocked, the heart takes longer to recharge. That’s why drugs like thioridazine, ziprasidone, and haloperidol carry higher cardiac risk. Even common ones like quetiapine and risperidone can do it, especially when stacked with other QT-prolonging meds.

Which Drugs Make the Risk Worse?

It’s not just antipsychotics. Think about how many people take multiple prescriptions. A patient on quetiapine for mood swings might also get ciprofloxacin for a sinus infection, ondansetron for nausea, or sertraline for anxiety. Each of those has its own QT-prolonging effect. Together, they don’t just add up-they multiply.

Here’s what the data shows:

• Thioridazine: High risk. Withdrawn in the U.S. in 2005 but still used elsewhere. Linked to nearly 8 times higher risk of sudden death.
• Ziprasidone and haloperidol: Moderate to high risk. Both strongly block hERG channels.
• Quetiapine and risperidone: Moderate risk. Widely prescribed, but dangerous in combination.
• Aripiprazole, brexpiprazole, lurasidone: Low risk. Much safer for the heart.

And the other culprits? Fluoroquinolone antibiotics like moxifloxacin, antiarrhythmics like sotalol, and anti-nausea drugs like ondansetron all contribute. One 2022 study found that combining an antipsychotic with an antiemetic like ondansetron stretched the QT interval by nearly 39 milliseconds-far more than either drug alone.

Who’s Most at Risk?

Not everyone who takes these drugs will have a problem. But some people are sitting on a ticking clock.

• Women: Their hearts naturally take longer to repolarize. Add a QT-prolonging drug, and the risk jumps.
• People over 65: Aging slows heart recovery. One study showed age adds 15 milliseconds to QTc.
• Those with low potassium or magnesium: Electrolytes keep the heart’s electrical system running. Low potassium (<3.5 mmol/L) can add over 22 milliseconds to QTc.
• People with slow heart rates (bradycardia): Fewer beats per minute means longer time between beats, which can artificially lengthen QT.
• Patients on multiple QT-prolonging drugs: The risk isn’t linear-it’s exponential. Studies show a 2.3 to 4.7 times greater QT prolongation when two or more are used together.

And here’s the kicker: 45% of people on antipsychotics are already taking at least one other drug that prolongs QT. That’s nearly half the population on these meds.

What Doctors Should Be Doing

Guidelines from the American Heart Association and American Psychiatric Association are clear: baseline ECG before starting high- or moderate-risk antipsychotics. Follow-up ECGs at 1 week, 4 weeks, and then quarterly if you’re on a single drug. If you’re on two or more QT-prolonging drugs? Weekly ECGs for the first month.

But here’s the reality: in community clinics, ECG compliance is below 35%. Why? Insurance denies coverage. Rural clinics don’t have the equipment. Clinicians are overwhelmed. One psychiatrist in Massachusetts told a forum she avoids disasters by checking potassium levels weekly and never prescribing combinations where QTc is already over 470 ms.

There’s a better way. Electronic health records can flag dangerous combinations before they’re prescribed. One study showed this cut risky prescriptions by over half. But the system also spat out 17.8 false alarms per 100 alerts-meaning doctors waste hours sorting through noise.

The Real Cost of Ignoring the Risk

In 2021, the FDA reported that 78% of torsades de pointes cases happened within 72 hours of starting a new combination. That’s not a slow burn-it’s an emergency waiting to happen.

One case from Cleveland Clinic: a 68-year-old woman on quetiapine 300 mg daily got a 5-day course of ciprofloxacin. Her QTc jumped from 448 ms to 582 ms in just three days. She went into torsades. She survived. But only because her ECG was checked early.

And it’s not just about saving lives. The National Alliance on Mental Illness found that 29% of patients stopped taking their antipsychotic because they were scared of heart damage. Many didn’t even know their actual risk. One patient said, “My doctor said it was ‘rare,’ but didn’t say how rare. I didn’t know if it was 1 in 100 or 1 in 10,000.”

What You Can Do

If you’re on an antipsychotic, here’s what to ask your doctor:

1. Is my medication high-risk for QT prolongation?
2. Am I taking any other drugs that could add to this risk?
3. Can we check my QTc with an ECG before I start or after any new prescription?
4. Should I get my potassium and magnesium levels checked?
5. Is there a lower-risk alternative? Aripiprazole, brexpiprazole, or lurasidone might be options.

Don’t assume your doctor knows all your meds. Bring a list-prescription, over-the-counter, even herbal. Some supplements, like St. John’s Wort or licorice root, can also affect heart rhythm.

The Future Is Safer

Change is coming. In May 2024, the FDA approved the first digital ECG patch designed for psychiatric patients. It’s small, wearable, and sends real-time QTc data to your doctor. No more waiting for clinic appointments.

By 2025, the American Psychiatric Association will roll out a risk calculator that factors in age, sex, electrolytes, and drug combinations to give you a personalized risk score. And by 2026, a genetic test will identify people who metabolize antipsychotics slowly-making them more vulnerable to buildup and toxicity.

Medicare is already tying 2.3% of payments to proper QT monitoring. That means hospitals and clinics will have financial reasons to get it right.

Low-risk antipsychotics like aripiprazole are growing in use. In 2019, they made up 22% of new prescriptions. By 2027, that’s projected to hit 52%. The tide is turning-not because the old drugs don’t work, but because we now know how to use them safely.

Bottom Line

QT prolongation isn’t a myth. It’s a measurable, preventable risk. The good news? You don’t have to choose between mental health and heart health. With the right checks, the right meds, and the right questions, you can manage both.

Don’t wait for a crisis. Ask for an ECG. Ask about your meds. Ask about alternatives. Your heart is worth it.