COVID-19 Linked to Lasting and Underrecognized Smell Impairment

Published October 10, 2025

COVID-19 Linked to Lasting and Underrecognized Smell Impairment

Patients may notice lasting changes to their sense of smell after SARS-CoV-2 infection. According to a study published in JAMA Network Open, these self-reports are often accurate indications of persistent olfactory dysfunction.

About 3500 participants aged 18 years or older in the Researching COVID to Enhance Recovery (RECOVER)–Adult study filled out surveys on their perceived olfactory abilities, and a subset then completed an identification test of 40 different odors. Among participants who reported an altered sense of smell after COVID-19, about 80% had at least partial loss, with 23% having severe or total loss.

The authors observed that many of those who didn’t report a change also had measurable dysfunction. About 66% of people who’d had COVID-19 but didn’t report sensory changes had some impairment to their sense of smell, as did 60% of those who hadn’t been infected, as confirmed with antigen testing. This suggests that unrecognized loss of the sense of smell is common in the general population and more so among those who’ve had COVID-19, the authors said. The study builds on findings suggesting an association between SARS-CoV-2 and olfactory dysfunction and notes that patients may underestimate their smell loss. Clinicians, the authors added, may consider formal smell testing for patients who’ve had COVID-19 to help guide counseling on potential risks, such as difficulty detecting hazards including smoke or spoiled food.

The findings corroborate prior survey studies suggesting that SARS-CoV-2 is associated with persistent olfactory dysfunction. Patients with persistent olfactory dysfunction after SARS-CoV-2 infection had lower gray matter volumes both in the olfactory cortex and in other brain regions related to cognitive, sensory, and emotion processing than those without olfactory dysfunction. Historically, postviral olfactory dysfunction has not been considered to carry the same risk for cognitive dysfunction as age-associated or neurodegenerative disease–associated olfactory dysfunction, but large-scale data on this question are lacking.

Olfactory dysfunction after Covid-19 may be associated with neurological changes in structural connectivity

Treatments for smell loss after SARS-CoV-2 infection, such as olfactory training, have shown some promise in facilitating recovery. Olfactory training encourages gradual recovery by repeated exposure to specific odors to stimulate neural pathways and is included in consensus guidelines for treatment. Platelet-rich plasma injections into the olfactory cleft are being studied with some early promising results. Adjunctive treatments have been explored with varying success, such as intranasal application of corticosteroids to reduce inflammation; sodium citrate, which may modulate olfactory signaling; and vitamin A supplementation, believed to support mucosal repair.