Reduced ability to detect or identify odours
Loss or reduction of the sense of smell is one of the most common early, non-motor symptoms of Parkinson's disease, often appearing years before tremor, stiffness or slowness develop.
It usually goes unnoticed by the person experiencing it. While it isn't a symptom that is specific to Parkinson's disease on its own, it can be a useful piece of the overall picture when it occurs alongside other features.
Key points
- Loss of smell (anosmia) or reduced smell (hyposmia) is one of the earliest recognised non-motor symptoms of Parkinson's disease. It can also be accompanied by reduced enjoyment or perception of flavour in food, since smell contributes significantly to taste.
- Loss of smell is considered a 'prodromal' symptom of Parkinson’s disease, meaning it often occurs before (often years before) the development of any movement symptoms such as tremor or slowness of movement (bradykinesia).
- It is thought to be related to early changes in the nervous system and brain areas responsible for processing smell.
- Many people do not notice their own loss of smell or reduced ability to detect, identify or distinguish between odours, until it is specifically tested or pointed out by a family member.
- There is no specific treatment to restore smell in Parkinson's disease; management focuses on safety (eg smoke and gas detection) and monitoring for other emerging symptoms.
Next steps:
Loss of smell is common and has many possible causes other than Parkinson's disease, including:
- ageing, which is independently associated with some decline in smell
- certain medications
- chronic sinus conditions, nasal polyps or allergic rhinitis
- head injury
- smoking
- viral infections affecting the nose or upper respiratory tract.
When to consider specialist review
Speak with your GP if loss of smell is accompanied by other symptoms such as:
Any combination of these would warrant a specialist review.
When to seek urgent help
Loss of smell on its own is not a medical emergency. However, seek prompt medical attention if a sudden loss of smell occurs alongside:
- confusion
- facial weakness
- severe headache
- vision changes.
These may indicate a separate acute problem requiring urgent assessment.