More than half of people who lose their sense of smell due to a virus will go on to have parosmia.

Although the exact reason parosmia occurs is unclear, the prevailing theory is that when the olfactory nerves (which connect your nose to your brain) are damaged by a virus, head injury, the connection between your nose and brain is broken.

When the nerves start to regrow, they may go to a different spot in the brain than before, resulting in a distorted sense of smell.

Parosmia is typically treated with something known as olfactory training or scent training, which involves inhaling a particular scent and thinking about what that scent should smell like. So, if you were inhaling the scent of lemon, you would try to remember what lemon smells like at the same time.

People who did scent training for six months showed “clinically relevant improvements” in their ability to accurately smell scents by the end of the trial.