The complete loss of smell can be defined as anosmia. This condition could be temporary or permanent. Though not a serious health condition, anosmia could lead to loss of interest in food.
Loss of smell due to damage to the brain or nerves can happen due to age, brain tumor or injury, hormonal imbalance, diabetes, Parkinson's disease or Alzheimer's disease. Nasal problems such as polyps or tumor can lead to loss of smell or impaired smell.
Surgery can be done in case of nasal blocks. Antihistamines to treat allergies that cause loss of smell.
Bibliography / Reference
Collection of Pages - Last revised Date: February 19, 2019