The COVID-19 pandemic introduced a widespread and often distressing symptom: the loss or distortion of the sense of smell. While many individuals experienced a temporary loss (anosmia) or a distorted sense of smell (parosmia) during their acute illness, for some, these changes lingered for weeks, months, or even longer. This can significantly impact quality of life, affecting the enjoyment of food, the ability to detect hazards, and overall well-being. Fortunately, various strategies can aid in the recovery of this important sense.
How COVID Impacts Your Sense of Smell
The SARS-CoV-2 virus, which causes COVID-19, affects the sense of smell primarily by impacting supporting cells in the nose, rather than directly infecting the olfactory neurons themselves. These sustentacular cells are crucial for the olfactory system’s function and regeneration. The virus uses the ACE2 receptor to enter these supporting cells, leading to inflammation and damage within the nasal cavity.
This indirect effect on supporting cells can disrupt the environment necessary for olfactory neurons to detect and transmit smell signals to the brain. The temporary nature of smell loss for many individuals aligns with the body’s ability to regenerate these supporting cells.
Smell Training and Home Approaches
Smell training is a recommended method to help regain a lost sense of smell after a viral infection like COVID-19. This involves repeatedly smelling distinct odors to stimulate the olfactory system and encourage nerve regeneration. The standard approach typically uses four specific scents: lemon (or other citrus), rose, eucalyptus, and clove. These represent different odor categories, providing broad stimulation.
To perform smell training, individuals should sniff each of the four chosen scents for about 15 to 20 seconds, taking gentle sniffs, twice a day. It is beneficial to visualize or recall the memory of how each scent used to smell while sniffing. Consistency is important, with training often recommended for three to six months. Some protocols suggest switching to new scents after a few months to continue challenging the olfactory system.
Many people experience gradual improvement over time. Saline nasal rinses can also help clear nasal passages and reduce inflammation, aiding recovery.
Understanding and Managing Parosmia
Parosmia is a qualitative smell disorder where familiar odors become distorted and often unpleasant. For example, pleasant smells like coffee might smell like rotting meat or chemicals. This condition often appears two to three months after initial COVID-19 infection, sometimes as the sense of smell begins to return. It can indicate that olfactory nerves are attempting to recover, but signals are being misinterpreted by the brain.
Managing parosmia involves identifying and avoiding specific trigger foods and smells that cause distress. Common triggers include coffee, onions, garlic, roasted meats, and eggs. Experimenting with food temperatures can also be helpful, as heat stimulates the release of more odor compounds, making cold or room-temperature foods more tolerable. Bland textures and simple foods may be easier to consume temporarily. Parosmia improves over time, with many people experiencing resolution within several months to two years.
When Professional Help is Needed
While many recover their sense of smell naturally or with home-based strategies, professional medical consultation is advisable in some instances. If smell dysfunction persists beyond a few months, worsens, or significantly impacts daily life, seeking help from a healthcare professional is recommended. A doctor can rule out other causes for smell loss and discuss treatment options.
Referrals to specialists, such as an Ear, Nose, and Throat (ENT) physician, may be considered for a more comprehensive evaluation. Medical interventions might include prescription corticosteroids, which can help reduce inflammation, though their long-term effectiveness for post-COVID smell loss is still being researched. Other potential therapies under investigation include oral supplements or novel nasal sprays, but more research is needed to confirm their efficacy.
Recovery timelines vary. Many see improvement within weeks to months, though for some, it can take over a year. One study showed approximately 86% of patients regained their sense of smell by four months, and 96% by 12 months.