What causes Problems with Smell ?
Most people who have a problem with smell have recently had an illness or injury. The most common causes are upper respiratory infections, such as the common cold, and chronic sinus or nasal disease. Other common causes are -  aging   - smoking  - nasal polyps   - head injury   - allergens such as ragweed, grasses, and pet dander  - hormonal disturbances  - dental problems  - exposure to certain chemicals such as insecticides or solvents   - medications such as antibiotics or antihistamines   - radiation for treatment of head and neck cancers  - diseases of the nervous system such as Parkinsons disease or Alzheimers disease.  aging smoking nasal polyps head injury allergens such as ragweed, grasses, and pet dander hormonal disturbances dental problems exposure to certain chemicals such as insecticides or solvents medications such as antibiotics or antihistamines radiation for treatment of head and neck cancers diseases of the nervous system such as Parkinsons disease or Alzheimers disease.