Jell-O can go bad, depending on the type of Jell-O, packaging and thickening agent used in the preparation of the dessert. How the Jell-O is stored also affects its shelf-life.
Unopened Jell-O mix can stay in the pantry for an indefinite period of time. If the Jell-O mix has been opened, it can last for between three to four months when stored in the pantry. Prepared Jell-O must be stored in the refrigerator and can be safely eaten for seven to 10 days. Pre-packaged prepared Jell-O can be stored unopened in either the pantry or the refrigerator. In the refrigerator, pre-packaged prepared Jell-O lasts between 12 to 18 months. In the pantry, this type of Jell-O can be stored safely for three to four months.