Loss of the sense of smell, a problem called anosmia (an-OWES-me-uh), is a common complaint seen by allergists. Smell actually makes up a significant portion of the sense of taste as well, so anosmia not only affects the ability to enjoy smells like coffee, but also significantly lessens one’s ability to enjoy food. Ugh.
In the image above, the olfactory nerve is the yellow structure at the roof of the nasal cavity. The olfactory nerve is responsible for the sense of smell. Anosmia can occur if the olfactory nerve is blocked by swelling from allergies or by nasal polyps. This usually results in gradual, partial loss of smell. Both of these causes can be treated and the ability to smell restored. Total, sudden loss of smell, especially when accompanied by an upper respiratory infection, suggests viral damage to the olfactory nerve. This may be irreversible.
If you have trouble smelling, an allergist can help you determine the cause and may be able to restore your ability to smell