Smell disorders

Our sense of smell is hugely important in our day-to-day functioning and our quality of life.  Despite this, we are often not very conscious of our sense of smell, and patients do not always realise their sense of smell has been affected until some time has gone by.  There are many reasons why someone's sense of smell may be reduced or altered, and it can help to see a specialist with an specific interest in the sense of smell for a full evaluation.

Sudden loss of sense of smell or taste may be a symptom of COVID-19. Self-isolate and follow current government guidance if you think you may have COVID-19.

Technical terms

Anosmia = absence of sense of smell

Hyposmia = reduced sense of smell

Parosmia = distortion of the way things smell

Cacosmia = an unpleasant odour that is not due to something in the environment

Phantosmia = perception of odours where no odour is present 

Diagnosis

There are many potential causes for an altered or reduced sense of smell. The specialist should take a detailed history of the patient's sense of smell concerns, including any other nasal symptoms, any history of head trauma, upper respiratory tract infections, other medical conditions and medications.

The sense of taste is often reduced alongside any loss of smell. This is because a large part of our ability to perceive detailed taste information is in fact delivered by our sense of smell: our tongue's taste buds only provide basic information on sweetness, saltiness etc.

A detailed examination of the nasal cavity and the olfactory region (where the nerve endings that detect odours reside) is then carried out with a fine endoscope (fibreoptic camera).  It can also be necessary to have a scan of the sinuses and base of skull.  It may be helpful to determine how severe the smell loss is using special tests.

Treatment

The treatment of smell disorders depends on the underlying cause.  If nasal or sinus inflammation (e.g. chronic rhinosinusitis or nasal polyps) is identified, this should be treated with medication or surgery if needed.  In some patients, a trial of a nasal steroid spray or oral steroid pills may be helpful.

For some patients no direct treatment of the cause is possible.  However, many of these patients benefit from smell training, a process that involves regular exercises to re-train and strengthen the sense of smell by repeatedly smelling known odours in a "mindful" way.

Support

For more information on smell disorders and smell training, as well as sources of support for individuals affected by smell loss, visit AbScent.org.