Read the label on almost any energy drink, and the most common ingredient you’ll find is caffeine. It’s the chemical that provides the jolt folks crave to boost their energy and endurance and make them feel more alert and focused. What’s more, the waker-upper drink is being guzzled by more people now than ever before, including younger kids and adolescents.

But health professionals express concerns about the safety of these drinks. “While energy drinks and energy shots may give you the energy boost that you desire, they may also produce some unwanted side effects,” say Erica Bub and Karla Shelnutt, researchers at the University of Florida IFAS Extension, and authors of a report on the popular beverages. They say the drinks can cause irregular heartbeat, jitteriness and difficulty sleeping, but that there isn’t enough research yet to state whether the carbonated beverages are unsafe.

To steer clear of any problems, the scientists advise energy drink devotees to chug them in moderation, don’t mix the stuff with alcohol or other caffeine-containing beverages, and do check with your doctor if you’re on medication or have a condition that may make imbibing these energy boosters unsafe.