Energy drinks are canned or bottled beverages sold in convenience stores, grocery stores, and bars and nightclubs (in mixed drinks). Most energy drinks are carbonated drinks that contain large amounts of caffeine and sugar with additional ingredients, such as B vitamins, amino acids (e.g. taurine), and herbal stimulants such as guarana.
Energy drinks are marketed primarily to people between the ages of 18 and 30 as a stimulant, which is why energy drinks have names that convey strength, power, and speed, and sexuality, such as: one of the most popular energy drinks, contains nearly 80 mg of caffeine per can, about the same amount of caffeine as a cup of brewed coffee and twice the caffeine as a cup of tea. Other energy drinks contain several times this amount. The amount of caffeine in an energy drink isn't always indicated on the label, so it is difficult to gauge how much one is consuming.
Another problem with energy drinks is that unlike hot coffee or tea, which is sipped slowly, it's common for typical energy drink consumers to drink large amounts quickly.
Some people are sensitive to caffeine and experience anxiety, palpitations, irritability, difficulty sleeping, and indigestion with relatively small amounts. People with heart conditions should avoid large amounts of
caffeine, because it is a stimulant.