We recommend that the oils be used within 120 days from the day you open the bottle. The oils might last much longer. The best way to know if the oil is still fresh is by smelling it. If its smells rancid is time to get a new bottle. In order to make sure that the oil is not rancid pour a bit of oil in a glass jar and smell it. This is a better test than smelling it directly from the bottle.