Tea expires after several years of storage. According to GlobalPost, as tea is left in storage, the natural oils that provide the flavor from the tea leaves evaporate, leading to a decreased scent and flavor of the tea.
The primary change as tea expires is the loss of flavor. In many cases, using multiple tea bags remedies this concern; however, bacteria can grow on tea, especially if it is not stored properly. As such, consumers need to approach expired tea with caution.
The way the tea is stored affects how long it lasts before weakening. Airtight containers limit the evaporation of the oils, and materials like glazed ceramics do not impart new flavors to the tea. Teas that are stored in such containers may maintain their flavor well after their listed expiration date.