Many people like to make tea in thermos cups, which is healthy and convenient, but there are actually many places to pay attention to. First of all, remember to change the tea in time. Although tea is very good, it can't be soaked in tea for a long time, which will actually make its own special structure have some variability. Because the thermos cup is basically in a closed environment for a long time, and if the tea leaves are closed inside, it is very likely to ferment, and the fermented tea leaves will actually produce bad substances. Therefore, tea must be replaced in time. Basically, after one or two rounds of drinking, new tea must be replaced. Otherwise, this harmful substance will do more harm to the human body and will not achieve the effect of drinking tea water for health. And in fact, overnight tea itself is not good for your health. In fact, overnight tea does not contain vitamins and other nutrients. In fact, drinking overnight water, let alone overnight tea, is not recommended. Therefore, after the tea has been soaked for a long time, it should be dumped in time, because over time, there will actually be some bacteria in it, and overnight tea is also easy to produce spoiled food in a thermos, which makes our body prone to diarrhea. After all, tea itself is cold. Moreover, it is best to buy a thermos cup with a special filter screen. It's not good to put the tea directly in a thermos without filtering it with water. On the one hand, it is inconvenient to clean, and there will be residual tea residue in the thermos cup over time. Actually, it is very unhealthy. So if you want to make tea in a thermos cup, you must have a small filter screen, so that we can clean it easily and there will be no residue. After all, the bottom of the thermos cup is too deep to clean.