IE 11 is not supported. For an optimal experience visit our site on another browser.

COVID-19 loss of smell can last up to 5 months, new research finds

While loss of smell and taste can be upsetting and annoying, experts say that many people will recover their smell and taste in time.
/ Source: TODAY

A few weeks after testing positive for COVID-19, Michele Clear was cleaning when she noticed something "weird." Even though she was using bleach, she couldn't smell it.

“I don’t know when I actually lost my smell. I just remember when I realized it,” the 50-year-old general manager of several hair salons from Kings Mountain, North Carolina, told TODAY. “I was like, ‘Oh my God, I can’t smell’ and then I realized that I couldn’t taste or smell.”

Nearly two months after having COVID-19, Clear still can’t smell, and food tastes bland, salty or vinegary. She discovered an expired container of buttermilk with the consistency of cottage cheese and was worried that the rank odor didn’t register with her.

“Normally you could smell that,” she said. “There was absolutely no smell.”

COVID-19 and smell

Clear is not alone. An abstract that will be presented at the American Academy of Neurology’s 73rd annual meeting in April found that loss of smell from COVID-19 occurs commonly and can last up to five months. The abstract reinforces what doctors have seen in people who had COVID-19.

“(Participants) described having had quite an important impairment of their sense of smell during their infections,” Dr. Johannes Frasnelli, a professor and chair of chemosensory neuroanatomy at the University of Quebec at Trois-Rivières and an author of the abstract, told TODAY. “Most people that have had COVID have a problem with their sense of smell.”

For their study, Frasnelli and his colleagues asked roughly 800 health care workers who had tested positive for COVID-19 to answer a questionnaire about smell and taste impairment five months after being diagnosed. They ranked their ability to smell and taste from zero to 10, with zero being “no perception” and 10 being “very strong perception.”

Prior to having COVID-19, most people reported their smell being about a nine. During infection it, dropped to about two. Most people said their sense of smell returned, but in many cases they did not feel as if they could smell as they once did. Over 18% of participants admitted they couldn’t smell at all.

“Because we included them five months after infection, we saw that an important portion of the patients — half of them — their sense of smell has not yet come back to normal,” Frasnelli explained. “We saw the 20% of the patients had actually pretty important impairment of their sense of smell.”

In other illnesses, such as a cold, mucous blocks the nose making it difficult to smell normally during the duration of the illness. But it seems that COVID-19 damages the olfactory system.

“It inflicts an inflammatory insult onto the nerve itself,” Dr. Anthony Del Signore, director of rhinology and endoscopic skull base surgery at Mount Sinai Union Square in New York, told TODAY.

The abstract's findings reflect what clinicians are seeing with people who had COVID-19.

“It supports what we've been hearing anecdotally,” Dr. Alison Morris, head of the UPMC Post-COVID Recovery Clinic in Pittsburgh and division chief of pulmonary, allergy and crucial care, told TODAY. “We still don't understand it fully at this point and why some people have it resolved quickly and then in other people, it seems to persist. This study suggests that it can persist — but can also get better.”

Del Signore says some of his patients admit that their loss of smell and taste persists longer than five months.

“We have a fair number of patients in my practice where they were actually infected last March … and they're still having symptoms of changes in the taste and smell,” he said. “(The abstract) just re-reassures us or reemphasizes the fact that we can expect longer-term symptoms with regards to the sense of smell and taste.”

While this might sound distressing to those saddened that coffee doesn’t have its warm aroma or food tastes metallic, the experts say that the abstract shows that olfactory changes are normal and that smell and taste can and do return.

“If you take it in the reverse, 30% of people have never experienced a loss of smell and after five months 80% will have recovered their smell,” Dr. Nicolas Dupré, a neurologist at Québec-Laval University and an author on the abstract, told TODAY.

The researchers plan to follow the participants to see what their sense of smell is like in the future.

“We are following up to see what percentage will have a definitive loss of smell,” Dupré said.

For those struggling with loss of smell, some suggest trying olfactory or smell training, where people inhale an essential oil or a strong scent, such as a spice, to try to retrain their olfactory nerves. Papers prior to COVID-19 show that smell training can work for people who lost that sense due to other infections and experts believe it can help those with COVID-19, too.

“They sniff the essential oils for 15 seconds in and out, which helps do almost like a rehabilitation on the nasal nerves, the smelling nerves, which helps to get it rebooted,” Del Signore said. “It helps with the reestablishing of that continuity of the nasal nerves to really get their sense of smell back.”

He said that researchers at Mt. Sinai are examining whether fish oil and omega-3 fatty acids help people who lost their sense of smell. In his own practice, he sometimes uses a nasal irrigation with a low-dose steroid, which reduces the inflammation that might contribute to loss of the sense of smell.

“It helps with the inflammation that might be in the nasal cavity or the inflammation that might be around the nerve itself,” Del Signore said.

While the paper normalizes longer-term loss of smell and taste, the experience is still annoying to those going through it. Clear smells cigarette smoke randomly, anywhere for five minutes to an hour, even though there's no one smoking.

“The smell comes very randomly. This is the most annoying part, ” Clear said. “No one has any answers.”