Cardiac arrest: While the Death by Caffeine calculator can show people how many energy drinks at one time would be lethal, this formula doesn’t apply to everyone. Those with underlying heart conditions have gone into cardiac arrest after just a few energy drinks. Before drinking energy drinks or caffeine, be sure to know your heart’s health.
Headaches and migraines: Too many energy drinks can lead to severe headaches from the caffeine withdrawal symptoms. Changing the amount of caffeine you ingest daily can cause more frequent headaches.
Insomnia: Energy drinks do a good job of keeping people awake, but when abused, they can cause some people to miss sleep all together. This lack of sleep causes impaired functioning and can be dangerous to drive or perform other concentration heavy tasks.
Type 2 Diabetes: Because many energy drinks are also very high in sugar, they can eventually wear out the insulin producing cells of the pancreas, which leads to type 2 diabetes.
Drug interaction: Some of the ingredients in energy drinks can interact with prescription medications especially medications taken for depression.
Addiction: People can become addicted to caffeine and energy drinks. This can lead to lack of functioning when unable to have the energy drink or a financial stress from having to buy several energy drinks daily.
Risky behaviour: There was a study published in The Journal of American College Health which showed that teens are more likely to take dangerous risks when high on caffeine. This could result in injury or legal trouble.
Jitters and nervousness: Too much caffeine from energy drinks causes some people to shake and be anxious. This can interfere with performing needed tasks or cause emotional issues. A study out of Perth, Australia found that even just one 250ml energy drink can increase anxiety in young men.
Vomiting: Too many energy drinks can lead to vomiting. This causes dehydration and acid erosion of teeth and esophagus if frequent.
Allergic Reactions: Because of the many ingredients in energy drinks reactions could occur, from minor itching to airway constriction.