Changes in the Sense of Smell

The sense of smell (olfaction) is one of the five senses we have. We use our nose to smell and often when we lose or have an altered sense of smell, it is due to a nose or sinus problem.

We smell when smell chemical molecules (odorants) enter the nose and bind to the smell nerves at the roof of the nose. There they trigger nerve signals to the front part of the brain. Interestingly, the smell system is intimately connected with the emotional and memory parts of the brain and that is why smelling something familiar can often trigger strong memories and nostalgia.

Loss of smell (anosmia) can be due to a number of different conditions.

The most common causes for loss of smell are:

  1. Nose and sinus conditions like nasal polyps or sinusitis (25%)
  2. Viral upper respiratory tract infection (20%)
  3. Head injury (15%)
  4. Parkinson’s or Alzheimer’s disease (5%)
  5. Unknown causes (25%)
  6. Others like brain tumour, liver disease, diabetes, thyroid disease (10%)

If you have lost your smell (anosmia), have a reduced sense of smell (hyposmia) or smelling foul things or altered sense of smell (cacosmia), you should see an ENT doctor for nasoendoscopy to make a diagnosis and start treatment as soon as possible to restore the sense of smell.