---

A blocked nose and loss of smell is commonly caused by a cold, allergy, sinus infection, or poor air quality. Other causes for this condition (which is known as anosmia) may include nasal polyps (small noncancerous growths in the nose and sinuses that block the nasal passage), injury to the nose and smell nerves from surgery or head trauma.

Normal aging is often the cause of a progressive, complete, and permanent loss of smell. However, anosmia may be caused by temporary or permanent irritation or destruction of the mucous membranes inside of the nose. Receptors in the mucous lining that provides you with your sense of smell, known as the olfactory system, is vital for sending information through nerves into your brain. If any part of the olfactory system is damaged or destroyed, you may lose your sense of smell. This can happen as a result of:

• · Aging
• · Alzheimer's disease
• · Brain aneurysm
• · Brain surgery
• · Chemical exposures to certain insecticides or solvents
• · Diabetes
• · Huntington's disease
• · Kallmann's syndrome (inability of testicles to produce sperm)
• · Klinefelter syndrome (a condition in which males have an extra X chromosome in most of their cells)
• · Korsakoff's psychosis (a brain disorder caused by the lack of thiamin)
• · Malnutrition
• · Medications (for example, some high blood pressure medications)
• · Multiple sclerosis
• · Multiple system atrophy (a progressive disorder of the nervous system)
• · Paget's disease of bone (a disease that affects your bones, sometimes facial ones)
• · Parkinson's disease
• · Pick's disease (a form of dementia)
• · Radiation therapy
• · Rhinoplasty
• · Schizophrenia
• · Sjogren's syndrome (an inflammatory disease that generally causes dry mouth and eyes)
• · Traumatic brain injury
• · Zinc deficiency