Loss of smell and taste may persist after Covid or come back differently

Before the pandemic, Dr. Jennifer Spicer relished waking up early. In those quiet morning hours, she spent precious time alone with her dog and brewed a cup of her favorite coffee, using beans from an Atlanta roaster.

Now she can barely take a sip without spitting out the coffee. Once a source of taste pleasure, his coffee now has a chemical smell and taste that Spicer can no longer tolerate.

“I can’t even go to a cafe. It smells so bad,” said Spicer, assistant professor of infectious diseases at Emory University School of Medicine. “It’s really horrible.”

Comprehensive coverage of the coronavirus outbreak

Spicer’s abrupt change in senses now has one all too common culprit: Covid-19. She had a relatively mild case of the virus last summer; In addition to losing her senses of taste and smell, she also had fever, chills, and fatigue for about a week. His smell and taste finally returned – but not like before.

Now, says Spicer, some foods and drinks smell and taste bad. Really bad.

“It ranges from an unpleasant chemical taste to a taste of rotten meat,” Spicer said, adding that a recent bite of cheese tasted like chalk. Things are starting to improve, but it has been almost six months since she was infected.

Spicer is far from the only one. A study published Wednesday in the Journal of Internal Medicine found that 86% of patients with mild forms of Covid-19 developed loss of taste and smell, compared with 4-7% of those with moderate to severe cases .

The research included more than 2,500 patients in France, Belgium and Italy. The majority recovered in about two months.

It is unclear why loss of smell and taste is more common in people with milder forms of Covid-19. The authors of the study hypothesized that these patients have higher levels of certain antibodies that could limit the spread of the coronavirus to the nose.

A different line of attack

Covid-19 is not the first disease to cause loss of taste or smell. A bad cold, the flu, and even bad allergies can cause nasal congestion that makes these senses unnecessary. But in these cases, using a decongestant can help, even if only temporarily.

This is not the case with Covid-19, experts say. Instead, the coronavirus dulls those senses through a different line of attack.

“This is an inflammatory process in the nerve itself or in the cells,” said Dr. Nina Shapiro, pediatric head and neck surgeon at UCLA Medical School.

A person’s sense of smell works like this: an odor molecule enters the nose and lands on a special type of tissue called the olfactory epithelium. This tissue is filled with neurons, which pick up the scent molecule and transport it through the olfactory bulb and into the brain, where it is interpreted as, for example, the scent of roses.

Related

Neurons are guided on this nose-to-brain journey by support cells that act as signposts, showing the way. But the supporting cells are covered with a receptor called ACE-2 – the main target of the coronavirus in human cells. It also makes support cells a primary target.

Experts hypothesize that the virus lodges in these cells, disrupting the path of neurons to reach their destination in the brain. When this happens, people lose their sense of smell. And the smell is directly related to how a person experiences the taste.

There is no guarantee that these nerve connections will ever find their way back to their normal channels. But the fact that at least one reaction is occurring – even if it means that a once-cherished smell now smells of chemicals – may be a good sign.

“We actually think these nerve endings are trying to grow and repair themselves,” said Dr. Bradley Goldstein, associate professor of head and neck surgery and communication sciences at Duke University School of Medicine in North Carolina. “They’re not sending the right signals yet, but things need to heal.”

Download the NBC News app for comprehensive coverage of the coronavirus outbreakk

The smell and taste of food aren’t the only sensory issues for people who have had Covid-19. Patients also had to go through scented soaps, detergents and deodorants.

The loss or change in smell can be annoying, yes, but Shapiro points out that it can be dangerous as well.

“If you have a gas leak, you can’t necessarily smell it,” she says. And if people lose their appetite because food tastes like cardboard or even rotten meat, they can develop vitamin deficiencies. Additionally, people may not know when the food has actually spoiled or even burned.

The other risk, Shapiro said, is depression. People take great pleasure in eating and drinking, as well as other bases of human happiness, such as the smell of flowers.

“Your nose influences your emotional state. It helps us navigate our world and makes us feel like we’ve come to the right place,” said Dr. Sandeep Robert Datta, associate professor of neurobiology at Harvard Medical School.

“People who lose their sense of smell are at real risk for psychological disorders, including depression,” he said.

Spicer, now six months into his own sensory issues, advises those in similar situations to seek support groups. “Learn about other people’s experiences, because it makes you less crazy,” she says.

“Honestly, you start to wonder, ‘Am I dramatic? Is it that bad? “

“Yeah,” she said. “It really smells so bad.”

Follow NBC HEALTH on Twitter & Facebook.