Most people never fully recover their sense of smell after COVID

Think your sense of smell never fully bounced back after COVID-19? You’re probably right. In a large, objective test of smelling ability, most people who noticed a change still scored poorly nearly two years later. Even many who felt fine turned out to be impaired.

A nationwide team working within the NIH RECOVER Initiative, coordinated by NYU Langone Health’s Clinical Science Core, put the long-running suspicion to a formal test.

Their study, published in JAMA Network Open, used a standardized 40-odor “scratch-and-sniff” exam to measure smell in 3,535 adults with and without a history of COVID-19. The result: olfactory problems after infection are common, surprisingly persistent, and often hidden.

Testing reveals hidden smell problems

Among participants who had COVID-19 and said their smelling was worse afterward, 80 percent posted low scores on the clinical test roughly two years later. Nearly a quarter of that group – 23 percent – were severely impaired or had lost smell entirely.

The surprise was how often problems turned up in people who felt normal. Sixty-six percent of previously infected adults who did not report any issues still scored abnormally low.

“Our findings confirm that those with a history of COVID-19 may be especially at risk for a weakened sense of smell, an issue that is already underrecognized among the general population,” said study co-lead author Leora Horwitz, MD.

She also noted that smell loss isn’t rare outside the COVID context: 60 percent of uninfected participants who denied any olfactory problems nevertheless performed poorly on testing.

Smell loss linked to disease

Hyposmia – a dulled sense of smell – is not a trivial nuisance. It’s tied to weight loss, reduced quality of life, and depression. It can blunt detection of spoiled food, gas leaks, and smoke.

Clinically, smell dysfunction can also precede neurodegenerative diseases such as Parkinson’s and Alzheimer’s, which affect the brain regions that process odors. Catching olfactory decline, especially when people don’t notice it, may offer a valuable early warning.

How the team measured smell

Participants took the University of Pennsylvania Smell Identification Test (UPSIT), the gold standard for clinical smell testing. The exam includes 40 microencapsulated scents. You scratch, sniff, and select the matching answer from multiple choices.

Each correct response earns one point. Researchers compare the scores with a large reference database matched by sex and age, classifying them as normal, mildly impaired, moderately impaired, severely impaired, or absent.

Adults enrolled in the RECOVER study completed detailed symptom surveys every 90 days from October 2021 through June 2025, and researchers layered the UPSIT results onto them. The design let researchers link real-world smell reports to clinical results across a very large sample.

People often misjudge smell loss

One of the clearest messages is that people often misjudge their own sense of smell. Many who believed they were fine were not, and many who sensed a problem were right that it had lingered.

That mismatch has significant implications for care. If clinicians rely only on self-report, they will miss many cases of impairment – especially in people who have had COVID-19.

“These results suggest that health care providers should consider testing for loss of smell as a routine part of post-COVID care,” Horwitz said. “While patients may not notice right away, a dulled nose can have a profound impact on their mental and physical well-being.”

New ways to recover

Researchers are testing ways to restore smell after viral injury. Two strategies show promise: vitamin A supplementation and structured olfactory training. This training involves guided, repeated exposure to specific scents designed to “rewire” perception.

A deeper understanding of how SARS-CoV-2 disrupts the brain’s sensory and cognitive systems could sharpen these approaches and inspire new ones.

Still, the current study leaves important gaps. The team did not directly measure taste, which often falters alongside smell.

Some “uninfected” volunteers may have had undocumented COVID-19, muddying the comparison. And while the UPSIT offers a rigorous measure, it captures only a snapshot in time, not the full trajectory of recovery or decline.

Lingering damage calls for testing

Taken together, the findings confirm what many have felt since early in the pandemic: COVID-19 can leave a long shadow on the senses. Some damage fades, some lingers, and some hides in plain sight. Objective testing brings that shadow into clearer view.

The practical takeaway is simple. If you’ve had COVID-19 – especially if you noticed a change in smell – ask your clinician about getting tested. If you didn’t notice a change but have nagging issues with appetite, enjoyment of food, mood, or safety cues at home, consider testing too.

For health systems and clinicians, making smell checks part of routine post-COVID care could catch problems early and open the door to support.

And for everyone else? Pay attention to your nose. It does more than flavor your coffee in the morning. It helps keep you safe, nourished, and connected to the world – reasons enough to check in on it, even if you think it’s fine.

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