The duration of effectiveness of a syrup like Tylenol or a cream like Polysporin after opening varies. Typically, syrups are stable for up to 1 year after opening or until the expiration date indicated by the manufacturer, whichever comes first. Similarly, tubes of cream are usually effective for up to 1 year or until the manufacturer's expiration date, depending on which date comes first. It is important to store these products in ideal conditions, such as in a cool and dry place, and not in a bathroom or kitchen.