When we’re tired, it’s natural to look for something to help us wake up. A morning cup of coffee is essential for many adults. Some prefer tea or an energizing breakfast. A brisk workout even helps some people gain the energy they need to push through the midday slump. For others, caffeinated sodas or sugary energy drinks are their go-to.

Some of these techniques are healthy, such as exercise or even coffee in moderation, but some of them are far more damaging than many people realize. You might want to think twice before reaching for an energy drink.

Energy drinks may wake you up, but they have a lot of negative side effects. For starters, they make it possible to overdose on caffeine, which can lead to problems like nausea, high blood pressure and even death. A high caffeine intake also reduces insulin sensitivity which can lead to type 2 diabetes. Dentists will also warn that the high amounts of sugar and acid in energy drinks can damage your dental health.

Dan Royals is an Australian who currently lives in Asia and works as a teacher. He knows first hand about the dangers of drinking energy drinks. He used to drink 5 or 6 energy drinks to make it through the day. Then he noticed that he was getting blisters on his tongue, and the skin was even peeling. Alarmed, he went to his dentist.

His dentist told him that the damage to his tongue was caused by his excessive consumption of energy drinks. He said that the ingredients in the energy drinks, including amino acids, B vitamins, sugar and herbal substances were literally eating his flesh.

To try to prevent other people from experiencing the damaging effects of energy drinks, Royals took to Facebook and posted a picture of his tongue as a warning. Along with the picture, he wrote,

Who drinks energy drinks? Addicted to them? You may want to think again…Up until recently when this started to occur I was drinking at least 5-6 a day (lack of energy teaching kids usually) and I brush daily, went to the doctor and boom! Found out it’s the chemicals in these drinks that are causing it… It literally eats away at your tongue.

Even though Royals admits to smoking cigarettes, he insists that they have nothing to do with the tongue damage and that the energy drinks are to blame.

Does the picture of Royals’ tongue make you wary of drinking energy drinks? Did you know energy drinks had so many negative side effects? What’s your go-to trick when you need an energy boost?