Five kinds of black tea can be drunk for a long time, but the following points should be noted:

1. Drink in moderation, and do not exceed 1-2 cups a day.

2. Pay attention to the quality of tea, choose high-quality black tea, and don't buy expired tea or tea doped with other impurities.

3. Pay attention to cleaning before drinking and keep your mouth clean.

4. Pay attention to personal physique, and stop drinking if you feel unwell.

Generally speaking, black tea is a healthy drink. Drinking in moderation can bring many benefits, but it is also necessary to pay attention to usage and precautions.