2. Respiratory Viral Infection
Anyone who’s suffered a bad cold or flu knows that it can cause slight or significant loss of smell, or anosmia. That’s because these kinds of infections can actually result in damage to the interior lining of the nose and sinuses, making it difficult for a person to detect odours.
Viral infections of the upper respiratory system are particularly problematic in this regard. While they often lead to anosmia, in most cases the result is parasmia, or a distorted sense of smell that can cause sufferers to react negatively to typically pleasant smells. This is caused by damage to the olfactory receptor cells. The good news is that effective treatment of the source infection typically leads to positive long-term outcomes.