Common Causes
| Cause | Details |
|---|---|
| COVID-19 | Sudden, often complete loss without nasal congestion — a hallmark early symptom |
| Common cold/sinusitis | Congestion blocks smell receptors — most common overall cause |
| Nasal polyps | Chronic blockage of nasal passages |
| Ageing | Gradual decline in smell sensitivity is common with age |
| Head injury | Can damage the olfactory nerve |
| Neurological conditions | Parkinson's disease often causes smell loss years before motor symptoms |
| Medications | Some drugs affect taste/smell as a side effect |
Smell Training — Evidence-Based Recovery Technique
Smell training involves sniffing 4 distinct strong scents (commonly rose, lemon, clove, eucalyptus) for 20 seconds each, twice daily, for several months. Clinical trials show this can meaningfully improve recovery of smell function, particularly after viral-induced anosmia.Safety Considerations
- Install smoke and gas detectors — loss of smell removes an important safety warning system
- Check food expiry dates carefully rather than relying on smell to detect spoilage
- Be extra cautious with gas appliances
Parosmia — A Distressing Recovery PhaseSome people recovering from viral-induced smell loss experience parosmia — distorted smell perception where normal smells (coffee, meat, onions) become unpleasant or disgusting. This is a recognised part of nerve recovery and typically improves over months, though it can be very distressing.
How long does COVID-related smell loss last?
Most people recover smell within 2-4 weeks, though a significant minority experience symptoms for months, and a small percentage have persistent, long-term changes.
Can loss of smell be a sign of a serious brain condition?
Gradual loss of smell can be an early feature of Parkinson's disease or Alzheimer's, sometimes preceding other symptoms by years. However, this is just one of many possible causes, and isolated smell loss is far more commonly due to nasal or viral causes.
Does taste loss always accompany smell loss?
Yes, in most cases — much of what we perceive as 'taste' is actually smell (retronasal olfaction). True taste (sweet, salty, sour, bitter, umami) detected by taste buds is usually preserved even when 'flavour' perception is lost.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.