Love your cola? Well too much of it can affect your muscles. According to a new study, heavy cola consumption can increase risk of hypokalemia—low blood potassium levels—that can create problems in muscles and nerve function. A person with hypokalemia can experience symptoms that range from weakness to serious paralysis.

Researchers from the University of Ioannina in Greece conducted a study of people who drank between 2 to 9 liters of cola a day. During the study, doctors admitted two pregnant study participants to the hospital. The first woman suffered from fatigue, appetite loss and constant vomiting while the other participant experienced increasing muscular weakness. Both women had low potassium levels.

Moses Elisaf, MD, of the University of Ioannina, said that ingredients in cola, such as glucose, fructose and caffeine, contribute to hypokalemia. “However, in most of the cases we looked at for our review, caffeine intoxication was thought to play the most important role,” Elisaf said. “This has been borne out by case studies that focus on other products that contain high levels of caffeine but no glucose or fructose.”

But don’t bypass caffeine-laced colas and reach for their caffeine-free counterparts. Elisaf also stressed that caffeine-free cola products can also cause hypokalemia because they contain fructose.

“The fructose they contain can cause diarrhea,” Elisaf explained.