You can drink black tea when you have your period. First, black tea itself has diuretic effect. During menstruation, the changes of hormone levels in women will lead to the phenomenon of water and sodium retention, so drinking black tea has diuretic effect and reduces the symptoms of water and sodium retention. Second, black tea has anti-inflammatory and bactericidal effects. During menstruation, the body's resistance and immunity are low. If you don't pay attention, some pathogens will invade the uterine cavity, causing endometritis and even pelvic inflammatory disease. So drinking some black tea can sterilize and diminish inflammation. Third, black tea can also eliminate fatigue. During menstruation, you will be in a state of fatigue. Drinking some black tea properly can make your body rest and relax.