Black tea is food, can not talk about side effects, is possible to drink in moderation; as long as it is not a long time to drink too strong black tea, generally no harm, but drinking too strong black tea may affect the iron absorption, resulting in insomnia. Black tea is rich in caffeine, tea polyphenols, etc., moderate consumption, beneficial to the human body; at the same time, black tea after fermentation nutritional value is relatively high, containing rich tea polysaccharide complex, theaflavin and thearubigin, moderate consumption can be supplemented for the human body. However, it is not recommended to drink too strong or too much, there may be some side effects. Drinking black tea for a long time or drinking too strong drinking tea may also have some disadvantages. Black tea contains ellagic acid, ellagic acid will combine with ferritin to form insoluble substances, long-term drinking black tea will affect iron absorption; in addition, black tea contains theophylline, theobromine and caffeine, long-term drinking black tea may cause nervous excitement, which can lead to insomnia. Overall, black tea contains many nutrients in favor of the human body, the human body still has many benefits, but not all people are suitable for drinking black tea, for pregnant lactating women are not recommended to drink black tea.