If you drink more than three cups of coffee at a time, you will feel nervous, anxious and short of breath. If you drink more than ten cups, it will cause poisoning, such as dizziness, tinnitus, elevated blood pressure, blurred vision, rapid arrhythmia, and even nervous disorder and muscle tremor. The dose of caffeine poisoning is generally 0.5 ~1g.

Extended data:

The doctor warned not to drink coffee on an empty stomach, because coffee can stimulate gastric acid secretion, especially for patients with gastric ulcer. Coffee, as a drink, should be properly drunk according to personal circumstances. Generally speaking, in nutrition, we still emphasize a balanced diet rather than spicy food.

In addition, it is worth noting that patients with hypertension should avoid drinking caffeinated drinks when their work pressure is high. Because caffeine in coffee may lead to high blood pressure, if coupled with emotional tension, it will have a dangerous multiplier effect.

Reference link: moderate use of coffee will not increase the risk of heart disease-People's Daily Online