Smell and Taste Disorders - Causes

Authored by Dr Hayley Willacy, 01 Jun 2017

Reviewed by:
Dr Carl Philpott, 01 Jun 2017

Sometimes a cause for the loss of smell cannot be found. This happens in about 1 in 5 people who are investigated in a specialist clinic, but in the wider community represents fewer than 5 in a 100 of all cases of smell loss overall. The sense of smell can be lost due to a variety of causes. The most common causes include:

  • An injury to the head.
  • A stroke.
  • Viral infections - colds or flu.
  • Diseases affecting the sinuses, such as allergies, various forms of sinusitis (including where nasal polyps form), and structural abnormalities.
  • Taking certain medications - see below.
  • Hormone problems such as Cushing's syndrome.
  • Dental or mouth problems.
  • Exposure to certain chemicals such as benzene, chlorine, formaldehyde, paint solvents and trichloroethylene.
  • Exposure to radiation therapy for head or neck cancer.
  • Cocaine snorted through the nose.
  • Cigarette smoking.

Some other medical conditions may be associated with a complete lack of sense of smell (anosmia), such as epilepsy, Alzheimer's disease, Parkinson's disease and schizophrenia.

The sense of smell, as with all other senses, naturally regresses with age. Rarely, some cancers can also cause anosmia.

There are some conditions that can affect your smell or taste temporarily. Short-term changes in smell and taste are common with infections affecting your upper respiratory tract, like colds and sinus infections. If this is the cause your smell and taste should generally return within two weeks. If you are worried about a persistent change in your sense of smell or taste, you should make an appointment with your GP.

Your GP will ask you about what exactly has happened and then may examine your nose, mouth and neck. They can then decide whether you should be referred to an ear, nose and throat (ENT) surgeon for further assessment, investigation and advice.

A physical examination will be performed in the ENT clinic. This will often include an endoscopic examination of the nose. More specific tests of smell may be performed. Other tests may include:

  • Measuring the lowest strength of a chemical that a person can detect.
  • Comparing smells of different chemicals to distinguish one from another.
  • Identifying smells.
  • Taste tests where taste solutions are applied to each side of the tongue in turn.

Patients can also be tested for nasal allergies. Occasionally, computerised tomography (CT) scans or magnetic resonance imaging (MRI) scans may be requested to help reach a diagnosis, as well as a blood test.

Hello,Suffering for 2 years with sensation of thick mucus stuck at the back of the nose, which I'm often able to hock up out of my mouth (clear but very "snotty" and like thick glue when it's in a...

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