Yes. Caffeine levels in black teas vary depending on the type and brewing time but generally speaking, if you drink more than 4 cups of tea per day, you could be getting close to 400 mg of caffeine, well above the recommended daily dose of 300 mg or less. Consuming this amount could bring about some side effects, such as headaches, insomnia, irritability, and palpitations. So while there are health benefits associated with moderate consumption of caffeinated black tea, including improved alertness and digestion, it’s important to keep your intake at a reasonable level for optimal well-being. Be sure to read labels carefully so you’re aware of exactly how much caffeine each cup contains!