The harm of black coffee is mainly caused by inappropriate drinking, such as too high a concentration or drinking too much may be over-excited, drinking on an empty stomach may damage the gastrointestinal tract and so on. 1. Excessive excitement: black coffee contains caffeine and other substances that can strongly stimulate the central nervous system, so drinking at night, drinking too high a concentration, drinking too much may cause excessive excitement of the organism. It not only affects the normal rest of the body, but sometimes even cardiovascular symptoms such as palpitations. 2. Damage to the gastrointestinal tract: drinking espresso on an empty stomach will induce gastric acid secretion, which in turn will damage the gastric mucosa to a certain extent, and may aggravate gastric ulcers and other serious lesions. In addition, people with hypertension and other cardiovascular pathologies, pregnant women, children and other special groups should be cautious of drinking coffee, so as not to aggravate the condition or cause other adverse consequences. To summarize, when drinking black coffee in daily life should pay attention to reasonable drinking, the more sensitive to black coffee people can add milk, coconut milk, and so on.