One of the most intriguing symptoms of COVID-19, has been patients reporting a loss of their sense of smell.
Some experts estimate that the loss of the ability to smell (anosmia) affects as many as 70% to 80% of people who catch COVID-19 and seems particularly common among those with mild disease.
This may only last a few days or a few weeks. Unfortunately, for around one-third, the loss of the fifth sense can last for months.
Why does COVID-19 cause anosmia?
French researchers have shown that the virus that causes COVID-19 is present in the lining of the nasal passages as well as the sensory neurons. It is the nervous system cells that enable the brain to interpret scents. The presence of the virus in this olfactory system clearly shows that the virus can kill these sensory neurons. The need to grow new ones explains why it can take a while for people to recover their sense of smell after an infection.
How anosmia can cause problems
A study from the University of East Anglia found that losing ones sense of smell increases levels of stress and depression. People who experience this have high rates of depression (43%) and anxiety (45%), as well as problems with eating (92%), isolation (57%), and relationship difficulties (54%). Not only that, but losing one’s ability to smell can be dangerous - it means those affected cannot detect if food has spoiled, or if there is a gas leak.
What can you do about losing your sense of smell?
There are no proven treatments for restoring the sense of smell, although research is underway. It’s complex because each scent is composed of thousands of chemicals in different concentrations, each activating different patterns of brain cells.
However, according to charity Fifth Sense, you can take steps to boost your sense of smell, by smell training - taking time to retrain your nose and actively sniffing the same four scents every day, spending around 20 seconds on each scent and really concentrating on what you’re doing. This isn't a surefire cure, but many people have had success. Research indicates smell training can facilitate a speedier recovery and may help individuals who wouldn't otherwise have regained their smell. The general consensus is, the sooner you begin smell training the better. A few weeks after anosmia sets in, rather than a year or two will have better results.
You can use familiar smells to help (such as coffee or your usual soap), although Fifth Sense say that many of the smell training research studies have used the same four smells – lemon, rose, clove and eucalyptus.
Fifth Sense explains: ‘Essential oils are suggested because they are a stable source of odour that can keep for weeks in sealed vials/jars.
Do essential oils cure anosmia?
Whether the essential oils have any therapeutic effect in Smell Training is unproven.
Anosmia aside, there have been studies of individual oils which indicate they have therapeutic properties. Essential oils are complex chemical compounds made up of hundreds of separate substances. These can be classified into different chemical families - antifungal, antibacterial, antiseptic and antiviral - these determine the aroma and therapeutic properties of individual oils.
In aromatherapy (the holistic practice of the use of aromatic plant extracts and essential oils for healing), essential oils are selected for their therapeutic qualities. The aroma triggers a specific effect. Essential oils are made up of very small molecules, they are able to penetrate into our blood stream, which aromatherapist say aid many problems, for example enhancing blood circulation and problems such as acne, eczema and ageing skin.
Can essential oils boost mood?
Essential oils also act upon the limbic part of the brain (to do with emotions and feelings, which may explain why those suffering from anosmia report high levels of depression - being deprives of scent is clearly bad for our mental health). “Essential oils can have a dynamic effect on your mood through their aromas,” says Geraldine Howard, President and co-founder of Aromatherapy Associates. “The sense of smell is the most primitive of our senses, and is linked to the deepest parts of the brain that governs basic instincts, memories and emotions.”
The properties of smell training oils
- Lemon oil, is extracted from the rind. It has a cleansing effect on the body and mind. According to a research, lemon essential oil was proven to have powerful calming and mood-improving qualities.
- Rose oil may be used effectively to reduce anxiety, stress, depression, and pain. increase libido. protect against harmful bacteria and fungi.
- Clove oil has traditionally been used as an antimicrobial, to help kill bacteria, for pain relief, such as toothache, for digestive upsets and to relieve respiratory conditions like cough and asthma.
- Eucalyptus oil is included in over-the-counter cough medications have eucalyptus oil as one of their active ingredients, and can help respiratory complaints, sinus problems and hay fever.