1. Black coffee should not be eaten with foods rich in caffeine. The recommended intake of caffeine for healthy adults is usually less than 400 mg per day, while the caffeine content in black coffee is high, and 100 g contains 1.3 g of caffeine. If you eat too much with common foods rich in caffeine such as black tea, green tea, red bull and chocolate, you will be in danger of excessive caffeine intake. Causes dizziness, diarrhea, increased thirst, insomnia, headache, fever and irritability. In severe cases, dyspnea, vomiting, hallucinations, confusion, chest pain, irregular heartbeat or uncontrollable muscle twitching and spasms may occur.

2. Black coffee should not be eaten too much with alcoholic food. Common alcoholic foods are: alcoholic chocolate, tofu, fermented dumplings, beer, white wine, drunken crabs and so on. If black coffee is eaten too much with these foods, the caffeine in it will accelerate the absorption of alcohol by the human body, thus inducing alcoholism in the body, such as: deep coma, pale and cold skin, hypothermia, superficial slow breathing and other symptoms.

3. Black coffee can't be eaten with medicine. Caffeine in black coffee should accelerate human metabolism. If taken together with drugs, it may accelerate the absorption of drugs by the body or affect the effect of drugs on the body. So they should be eaten separately. Generally, it is best to drink black coffee every 6 hours during medication.