Olfactory nerves are the nerves between your nose and brain. A virus like COVID-19 can damage these nerves, resulting in a reduced or lost sense of smell. Fortunately, these nerves can regrow and repair themselves, and research shows that scent training speeds up the healing process.

Doctors may prescribe medications known as systemic corticosteroids to individuals with a lost or reduced sense of smell. These medications lower inflammation in the body and can help improve sense of smell in those who had COVID-19. While effective, systemic corticosteroids are expensive and can have unpleasant side effects including

• High blood pressure,
• Fluid retention or swelling, and
• Changes in mood and behavior.

A group of international researchers have recommended scent training in place of systemic corticosteroids. Scent Training is cost-effective, scientifically backed, and without side effects. Research shows that people who scent train develop increased cortical thickness in several regions of the brain which improves how they process smells and identify odors.

Even among people who didn’t get COVID-19, up to 30% of adults over 75 years of age experience a reduced sense of smell. Scent training can help older adults regain their sense of smell and improve cognitive ability, memory, and information processing.

Step 1. Choose one scented item from each of the four smell categories:

1. Floral: fresh flowers, plants, floral perfume, floral tea leaves or bags, and lavender, rose, chamomile, or jasmine essential oils
2. Fruity: lemon, lime, orange, grapefruit, lemongrass, and bergamot
3. Spicy: kitchen spices or oils such as clove, ginger, cinnamon, nutmeg, cardamom, or allspice
4. Resinous: coffee grounds, black pepper, and oils such as myrrh, benzoin, and frankincense

You may choose to buy a scent kit online or use items from around your house. Essential oils can be used for all four scent categories and will maintain their scent overtime. Choosing items that maintain their scent is important so that you know any perceived scent changes are due to improvements in your own ability, rather than changes in the items themselves.

Step 2. Smell your four items for 20 seconds each, at least twice a day. You may choose to scent train every morning and evening. Take short, light sniffs, and concentrate on the scent you are smelling.

It may take several weeks before you experience any improvement in your sense of smell. Even after four months of training, you may not go back to smelling things the way you used to, but you will likely see improvements over time. You should track your progress and note any changes in your ability, no matter how small. Another way to track your progress may be how you feel about smelling items, since smell and mood are closely linked.

If you constantly experience an unpleasant smell or the scent of burning rubber, you may have parosmia. This is a natural step in the healing process for your olfactory nerves, but it may take weeks to go away. Certain medications, brain injury, or infectious diseases such as influenza can also cause parosmia. When parosmia appears in someone who has had an impaired or absent sense of smell, this means their sense of smell is beginning to return.

A news article on scent training: Sixty seconds on . . . smell training

A website dedicated to scent training: Abscent

Peer-Reviewed Scientific Publications:

1. Zilstorff, K. (1966). Parosmia. The Journal of Laryngology & Otology, 80(11), 1102-1104. doi:10.1017/S0022215100066457
2. Aïn, S. A., Poupon, D., Hétu, S., Mercier, N., Steffener, J., & Frasnelli, J. (2019). Smell training improves olfactory function and alters brain structure. NeuroImage, 189, 45-54. doi:10.1016/j.neuroimage.2019.01.008