Caffeine is an alkaloid extracted from tea and coffee fruits. Moderate use can eliminate fatigue and excite nerves, and is clinically used to treat neurasthenia and coma resuscitation. However, large doses or long-term use can also cause harm to the human body, especially addiction. Once it is stopped, it will cause various withdrawal symptoms such as mental fatigue, fatigue and weakness. Although its addiction is weak, the withdrawal symptoms are not very serious. However, when the drug dose increases due to drug tolerance, caffeine will not only act on the cerebral cortex, but also directly excite the medulla oblongata, causing paroxysmal convulsions and skeletal tremor, and damaging important internal organs such as liver, stomach and kidney. Therefore, it is also included in the scope of psychotropic drugs controlled by the state. Caffeine abuse usually takes two forms: smoking and injection, and its excitability, side effects, symptoms and drug dependence are similar to those of amphetamine.