What other than sinus infections causes lost of smell?

Loss of smell, or anosmia, can be caused by several factors beyond sinus infections, including viral infections such as COVID-19 or the common cold, neurological conditions like Parkinson's disease and Alzheimer's disease, and head injuries that affect the olfactory system. Allergies and nasal polyps may also lead to a diminished sense of smell. Additionally, certain medications and exposure to environmental toxins can contribute to this condition.