Smell is a wonderful sense. It is intimately linked to our taste and our appreciation of foods and drinks. It is also an important sense for our safety, allowing us to detect gas, smoke, rotten food and other toxic chemicals.
Reduced sense of smell is called hyposmia. Complete loss of smell is called anosmia. All of us suffer loss of smell to some degree (hyposmia), usually with a common cold. More persistent loss of smell is often due to nasal blockage, caused by allergy, infection or inflammatory nasal polyps. Saline nasal washouts, steroid nasal sprays and surgery, can restore nasal function and smell.
Sudden loss of smell can occur as a post-viral illness condition. In this condition, the smell nerve cells are destroyed and no longer regenerate. This is a rare but devastating illness as loss of smell is permanent. Sudden loss of smell can also occur after a head injury.
Loss of sense of smell can be seen in diabetes, liver or kidney disease, Vit B12 deficiency, an underactive thyroid gland, autoimmune conditions and alcohol misuse. It can be seen with some medications such as some antibiotics, some antidepressants, anti-inflammatories and some heart tablets. It can occur after radiotherapy to the head and neck. In addition exposure to toxic chemicals, such as pesticides or solvents as well as cocaine and amphetamines can lead to loss of smell.
It can also be seen in people over 60, in epilepsy, Alzheimer’s disease, Parkinson’s disease, stroke and schizophrenia. Very rarely brain tumours can cause this. People who have had their voice box removed, and breath via a hole in the neck, are also unable to smell, as no air passes into the nose. Some people are born without sense of smell (congenital anosmia).
Unlike vision and hearing, there are no medical aids to help with the loss of smell.
Loss of smell has significant impact on quality of life, and appreciation of food, drinks and scent. Loss of smells that are of importance to us, such as a particular perfume of a partner, or the smell of our pets, is devastating. It can lead to loss of appetite and enjoyment of eating, with poor nutrition, loss of weight and even social withdrawal. Focusing on foods with different textures, and emphasis also on taste (sweet, sour, salt, bitter and umami (savoury flavour)) can help in providing variety and restore pleasure in eating food.
In addition, loss of smell makes gas in the home potentially very dangerous, as odour is added to gas so if there is a leak we can smell it. Gas detectors are useful, and converting the home to electricity energy is a safe, but expensive way or adjusting to living without smell. Fire alarms are needed at home also. Loss of smell can affect us in similar ways at work. In addition, it would be devastating for many occupations, e.g. a chef, chocolatier or a wine merchant.
Loss of smell makes it difficult to detect food that has gone off. People with anosmia need to pay close attention to expiry dates on food. They also need to be very mindful when handling bathroom and kitchen cleaners as well as insecticides and other toxic materials.
The future is an however is an exciting place. Doctors are now looking at transplanting smell nerve cells back into the noses of people who have lost their smell. One day, the cure for loss of smell will be out there.