The sense of smell is dependent on millions of specialized nerve cells that are replaced throughout our lifetime. But this isn’t always possible or complete. The most common causes of prolonged smell loss occur as a result of COVID-19, an upper respiratory infection, head injury, chronic sinus disease, and aging. However, other conditions such as Alzheimer’s disease, Parkinson’s disease, and tumors can be associated with smell loss. In cases where smell loss results from sinus disease, treating the sinus condition may lead to improvement. However, there are no specific medical treatments for loss of smell resulting from COVID, head injury, upper respiratory infection, or aging. If you experience any persistent change in your sense of smell, visit your doctor for an evaluation. Some rare forms of smell disorders may result from tumors in the brain, neurodegenerative disease, or infection. These conditions should be diagnosed expediently for proper management and treatment.