Yes, COVID-19 can cause partial or complete loss of smell, and it was one of the most distinctive symptoms of the pandemic’s early waves. During 2020 and 2021, roughly 38 to 43% of infected people experienced some degree of smell dysfunction. That rate dropped sharply with the Omicron variant, which causes smell loss at rates two to ten times lower than earlier strains, with a global prevalence estimated at just 3.7%.
Why the Virus Disrupts Smell
SARS-CoV-2 doesn’t appear to infect your smell-detecting nerve cells directly. Instead, it targets the support cells surrounding them. These support cells, called sustentacular cells, line the upper portion of your nasal cavity and express the ACE2 receptor the virus uses to enter cells. When the virus damages these support cells, the delicate environment your olfactory neurons need to function gets disrupted, even though the neurons themselves remain uninfected.
Think of it like pulling the scaffolding out from under a building. The structure is still there, but it can’t operate properly. Stem cells and blood vessel cells in the same area also carry the ACE2 receptor, which means the virus can interfere with both the maintenance and the blood supply of the smell-sensing tissue at the same time.
What Smell Loss Feels Like
Smell loss from COVID takes several forms, and they don’t always show up at the same time. Complete loss of smell (anosmia) is the most recognized version, but many people experience only a partial reduction. Both typically appear within the first few days of infection and may arrive before other symptoms like cough or fever.
For some people, the problem evolves during recovery into something more disorienting: distorted smell. This is called parosmia, where familiar odors smell wrong. Coffee might smell like gasoline, or cooking meat might smell rotten. Among people with persistent smell problems after COVID, about 50% experience parosmia. A related condition, phantosmia, involves smelling odors that aren’t there at all. Phantosmia affects a smaller but significant group, starting around 43% of those with ongoing dysfunction and gradually decreasing to about 24% over time. These distortions can be more distressing than having no smell at all, because they actively interfere with eating and daily comfort.
How Omicron Changed the Picture
Smell loss became far less common as the virus evolved. A systematic review comparing Omicron to earlier variants found the global prevalence of Omicron-related smell dysfunction in adults was roughly 3.7%, compared to 38 to 43% during the first year of the pandemic. The difference varies by population: people of European ancestry reported Omicron-related smell loss at about 11.7%, while other populations ranged between 1.9% and 4.9%. This shift is one reason smell loss is no longer considered a hallmark COVID symptom the way it was in 2020.
Recovery Timeline
Most people recover their sense of smell within 30 days of infection. But the gap between what people report and what objective testing reveals is striking. At six months, only about 5% of patients say they still have smell problems, yet when researchers test them with standardized scratch-and-sniff assessments, up to 69% still show measurable deficits. This suggests many people adapt to mild losses without fully realizing their smell hasn’t returned to normal.
At one year, roughly 26 to 42% still show some dysfunction on formal testing. At two years, about 28% do. In a longitudinal study where participants were tested an average of 838 days after infection, 55% still had some measurable smell impairment, with about 4% scoring in the range of total smell loss. The takeaway: full recovery is common, but a meaningful minority of people experience changes lasting well beyond a year.
Physical Changes in the Brain
In some cases, COVID-related smell loss corresponds to visible changes on brain imaging. MRI scans have documented shrinkage of the olfactory bulbs, the structures at the base of the brain that process smell signals from the nose. One documented case showed olfactory bulb volumes dropping from about 49 and 47 cubic millimeters to 30 and 36 cubic millimeters after two months of smell loss. Those post-COVID volumes fell below the minimum normal range reported in the medical literature for the patient’s age and sex. This kind of atrophy had previously been associated with other causes of long-term smell loss, but COVID provided a rare opportunity to compare pre- and post-infection brain scans in the same person.
The Emotional Weight of Losing Smell
Losing your sense of smell sounds minor compared to breathing problems or organ damage, but it reaches into daily life in ways people don’t anticipate. Food loses its appeal, cooking becomes frustrating, and the inability to smell danger signals like smoke or spoiled food creates real safety concerns. The loss also strips away emotional connections tied to scent: a partner’s skin, a child’s hair, fresh air after rain.
Research has linked COVID-related smell and taste loss to measurably higher rates of depression. One study tracking online communities found that people who reported these sensory losses and tested positive for COVID had a 30% higher risk of expressing depression compared to those without sensory symptoms. The mental health impact tended to peak more than 100 days after the initial infection, suggesting it builds over time as the loss persists rather than hitting immediately. Olfactory impairment has also been associated with reduced quality of life scores in broader research predating the pandemic.
Olfactory Training
The most widely recommended approach for recovering smell is olfactory training, a structured sniffing exercise. The standard protocol, used at major medical centers, involves smelling four specific scents twice a day, every day, for three months. The starting set is typically rose, eucalyptus, lemon, and clove. After three months, you switch to a new group: menthol, thyme, tangerine, and jasmine. After another three months, a third set: green tea, bergamot, rosemary, and gardenia.
You sniff each scent for about 15 to 20 seconds, trying to recall what it should smell like while inhaling. The idea is to retrain the connection between your nose and brain through repetition. Progress is slow and occurs over many months, sometimes up to two years. The evidence for olfactory training is encouraging but not overwhelming. It remains the intervention with the most consistent support, partly because it carries no risks and costs very little.
Medical Treatments
No medication has been proven to reliably restore smell after COVID. Intranasal corticosteroid sprays have shown a possible trend toward benefit in clinical trials, but the results are inconsistent and not statistically significant. Oral corticosteroids don’t appear to help. One small trial found that combining oral vitamin A supplements with olfactory training led to significant improvements within the treatment group, though more research is needed to confirm this. Other experimental approaches, including platelet-rich plasma injections and calcium-binding agents, have shown promise in limited studies but aren’t part of standard care.
If your smell loss persists beyond a few months, formal olfactory testing can help establish the degree of impairment. The most common tool is a 40-item scratch-and-sniff test that measures your ability to identify odors. Other tests assess your ability to detect faint concentrations of a scent or distinguish between similar odors. These evaluations give a baseline that can be compared over time to track whether you’re improving, which is especially useful since gradual recovery can be hard to notice on your own.