Living with anosmia: The problem of long-term loss of sense of smell

Approximate read time: 5 minutes

1. Impacts and risks of losing your sense of smell

Research has indicated that loss of sense of smell can significantly impact quality of life. A 2022 study from the University of East Anglia found “people who have lost their sense of smell report[ed] high rates of depression, anxiety, isolation and relationship difficulties”.^[1] Further challenges include:^[2]

• impacts on a person’s appetite, nutrition or relationship with food due to the close relationship between smell and taste
• being less able to tell if food is spoiled, and so risking food poisoning and illness
• not being able to smell gas in case of a leak, or smoke in case of fire or burning food
• not being able to smell the build-up of harmful fumes from products such as bleach or paint

2. Causes and prevalence of anosmia

‘Anosmia’ is the medical term for temporary or permanent absence of sense of smell.^[3] Some people have congenital anosmia—an inability to smell from birth—and many people experience a reduction or change in their sense of smell as they age. Others acquire changes through injury, medications, smoking, nose or sinus problems (like polyps) or viral infections. Some people experience parosmia, where smells experienced are different to what is expected. For example, pleasant or neutral smells are experienced as unpleasant. It is estimated that up to 20% of the population have some loss of sense of smell.^[4]

While colds and flus can temporarily cause loss of sense of smell, anosmia became recognised as a headline symptom of Covid-19 in May 2020, and for some people the loss of sense of smell was long-term or permanent.^[5] In 2022, it was estimated that 5% of the people who lost their sense of smell through Covid-19 infection experienced smell loss lasting for more than six months, resulting in approximately 15 million people with persistent smell dysfunction worldwide.^[6] In some cases, their sense of smell has never recovered.

For some individuals, anosmia was one symptom among others as part of long Covid, a post-viral condition where patients experience a range of issues, most commonly including fatigue, shortness of breath, problems with memory and concentration, palpitations, joint pain and muscle aches.^[7] Research from the University of East Anglia found that almost a third of self-reported long Covid patients were experiencing persistent smell loss.^[8]

Loss of sense of smell is also a potential sign of some psychiatric disorders and may constitute either a factor of vulnerability or a symptom. For example, studies have shown that people with major depressive disorder have reduced olfactory bulbs (the small structures just above the nasal cavity that process smell) and decreased smell sensitivity.^[9] Additionally, olfactory dysfunction can be a significant symptom in the early stages of psychiatric disease progression, including first episode psychosis and schizophrenia.

There are also associations between loss of sense of smell and neurological conditions including dementia and Parkinson’s disease. Abnormalities in the sense of smell often come before other noticeable symptoms. Research has related this to an overlap between the neural connections of the olfactory system and the parts of the brain that are associated with cognition, memory and emotion.^[10]

3. Research and treatment for anosmia

While some people recover spontaneously or respond to treatments for anosmia like steroids and nasal rinses, for others there is an opportunity to potentially ‘retrain’ their sense of smell through ‘olfactory training’.^[11] This was first proposed by neurobiologist Professor Thomas Hummel and colleagues in 2009.^[12] They asked patients to systematically smell four scents twice a day for 12 weeks: rose, eucalyptus, lemon and cloves. The study showed clinically significant improvements in 28% of patients, compared to 6% of the control group who spontaneously improved.

Positive results have been replicated in more recent studies involving post-Covid patients, in some cases combined with medication.^[13] There is also evidence that olfactory training could benefit some people in cases of age-related sensory decline or smell loss due to injury.

Another study, from University College London Hospitals in 2025, found that surgery increasing the nasal airflow into the olfactory region was effective in restoring sense of smell for some patients.^[14] There is also emerging evidence that injections of platelet-rich plasma, made from spinning a patient’s own blood in a centrifuge, could lead to nerve regeneration and therefore improvements in sense of smell.^[15]

The government has funded research projects through the National Institute for Health and Care Research (NIHR) looking at the prevention and treatment of loss of smell following Covid-19 and other viral infections.^[16]

4. Research into long Covid and related health conditions

The government has also provided research funding for long Covid more broadly.^[17]

The government said that in the financial years between April 2019 and March 2024, it had invested over £57mn into long Covid research through NIHR and the Medical Research Council.^[18]

In July 2025, the government published a delivery plan for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) which acknowledged its overlap (in terms of symptoms and potential treatments) with long Covid.^[19] The plan included a £1.4mn NIHR research programme exploring the cost effectiveness of existing healthcare models for both ME/CFS and long Covid with the aim of improving quality of care. It also announced a funding award for research to explore potential pharmaceutical treatments and repurposing of medications commonly used for other conditions. The government said “research is a gradual and iterative process, and we are committed to a long-term vision that supports sustained progress”.

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