Drinking too much coffee may have insomnia, stomach upset and other bad effects. 1. Insomnia: Because coffee contains a large amount of caffeine, this component has the effect of invigorating the spirit, eliminating fatigue, clearing the mind, if you drink too much may affect sleep, or even lead to insomnia. 2. Rapid heartbeat: the caffeine in coffee will also directly stimulate the cardiovascular center, leading to peripheral vasodilatation, and if you drink too much coffee, you may have a rapid heartbeat, or even arrhythmia and other phenomena. 3. Stomach upset: drinking too much coffee may stimulate the gastrointestinal mucosa and the secretion of gastric acid, and may cause stomach cramps if consumed in large quantities for a long time. Therefore, it is not advisable to drink too much coffee to avoid discomfort. If you experience serious discomfort after drinking too much coffee, you should go to the hospital in time.