Hydroxyzine QT Prolongation: Risks, Signs, and What You Need to Know

When you take hydroxyzine, a common antihistamine used for anxiety, itching, and nausea. Also known as Atarax or Vistaril, it’s often prescribed because it works quickly and doesn’t cause drowsiness in everyone. But for some, it can trigger a dangerous heart rhythm problem called QT prolongation. This isn’t just a side effect—it’s a signal your heart’s electrical system is off track. And if it gets worse, it can lead to a life-threatening rhythm called torsades de pointes.

QT prolongation, a delay in the heart’s electrical recovery phase seen on an ECG happens when certain drugs slow down the heart’s ability to reset after each beat. Hydroxyzine is one of them. It’s not the worst offender, but it’s not harmless either. People with existing heart conditions, low potassium or magnesium, or those taking other QT-prolonging drugs—like some antibiotics, antidepressants, or antifungals—are at higher risk. Even healthy people can be affected if they take too much or combine it with other meds. The FDA and other health agencies have flagged hydroxyzine in their lists of drugs that may cause this issue.

Most people won’t notice anything wrong. But if you start feeling dizzy, lightheaded, or like you’re about to faint—especially after starting hydroxyzine—you need to act. These aren’t normal side effects. They could mean your heart is struggling. Your doctor should check your ECG before prescribing hydroxyzine if you’re over 65, have a history of heart problems, or take other medications. Blood tests for electrolytes are also a good idea. Don’t assume it’s just anxiety or dehydration. A simple ECG can catch this early.

There’s no magic fix. If you’re on hydroxyzine and have risk factors, your doctor might switch you to a safer alternative like loratadine or cetirizine. These antihistamines don’t carry the same heart risk. If you’ve been taking hydroxyzine for years without issues, don’t panic—but do talk to your pharmacist or doctor. Review all your meds. Many people don’t realize they’re stacking drugs that all affect the QT interval. A single extra pill—a common cold med, an OTC sleep aid, or even a supplement—can push you over the edge.

What you’ll find in the posts below are real, practical stories and science-backed facts about how drugs like hydroxyzine interact with your body—not just your allergies, but your heart. You’ll learn how other medications can make this risk worse, what tests actually matter, and how to spot trouble before it’s too late. This isn’t about fear. It’s about awareness. And knowing the signs could save your life.