Tea has a shelf life, but it is related to the variety of tea. Different teas have different shelf life. Drinking tea is good for health, but drinking expired tea will do harm to the health.
In general, packaged tea will have a shelf life on the package. In this case, as long as the tea is in the indicated shelf life and is has kept in good condition, it can be safely consumed.
This usually refers to the loose tea and tea made by ourselves. First of all, we can observe the appearance and texture of tea. From appearance, if the tea expired and get mold, the color of tea may usually become white. From texture, most of the expired tea leaves are very light, and the flexibility is poor. Secondly, smell the tea leaves and observe the color of tea liquid. Expired tea leaves will give off a stale smell or a distinct different smell from the fresh tea; while the tea liquid will also become thicker and darker. For instance, green tea should has green appearance and clear tea liquid, if the tea become dark brown and the tea liquid goes darker and even turn red, then the tea are not drinkable anymore;