Caffeine is generally not toxic.

However, lower doses can also cause poisoning symptoms, about 1 gram, which is equivalent to drinking 20-50 cups of coffee, and some people who are not used to drinking coffee every day will react immediately. Some people are highly tolerant because they drink coffee every day and become poisoned only after drinking a large amount of coffee. The main symptoms occur in the central nervous system and cardiovascular system. Insomnia, restlessness and increased excitability are the initial manifestations, with people feeling unable to sleep, restlessness, discomfort and anxiety, followed by tachycardia, tinnitus and dizziness. Muscle tension, palpitations, etc. With the increase of the dose, there will be vomiting, spasms, coma and even death. Some people may die of shock or pulmonary edema with atelectasis or cardiac arrest. Children are more resistant to caffeine, and although high intake can lead to toxic symptoms, no deaths have been reported.