We're sorry that ZzzQuil didn't work for you, and we appreciate you taking the time to share this with us. ZzzQuil, like many other over-the-counter sleep medicines, contains diphenhydramine HCI, an ingredient used to treat occasional sleeplessness. Our product is found to be safe and effective when used as directed, so it's unexpected to hear that taking the product made your heart race, and we take reports such as this very seriously. For now, please discontinue use of the product and set it aside. If you have concerns with how the product is affecting you, be sure to consult your regular doctor or healthcare professional as they would be in the best position to advise you. Consumer safety is important to us, and our team would like to learn more about your experience to be able to assist you further; please hold on to the product, and give us a call at (877) 881-5813, anytime from 9:00AM-6:00PM EST Monday-Friday, so we can help!

We're sorry to hear about this, Shoocat. ZzzQuil products are quality-tested multiple times to ensure their effectiveness, so we take a report like yours seriously. Please call us at (877) 881-5813, as we hope to gather additional details and help you!