Loss of smell caused by colds, allergies or sinus infections usually clears up on its own in a few days or weeks. If this doesn't happen, make a medical appointment to rule out more-serious conditions.

Loss of smell can sometimes be treated, depending on the cause. For instance, an antibiotic can treat a bacterial infection. Also, it might be possible to remove something blocking the inside of the nose. But sometimes, loss of smell can be lifelong.