AUSTIN (KXAN) — Some people who have recovered from COVID-19 have not regained their senses of taste and smell – and doctors do not know when those senses might return.

The Centers for Disease Control and Prevention lists the loss of taste and smell as a common symptom associated with COVID-19, and studies show that roughly half of patients infected with COVID-19 lose those senses.

In some cases, patients who lost the ability to taste and smell while they battled the virus have still not regained those senses months later.

For those people, it may take as long as a year for their senses to come back – the loss may even be permanent, experts fear.

“So far, 10% of people do not look like they recover it quickly and we don’t know long term if they will or if they won’t,” said Dr. Rachel Arffa, a rhinologist and otolaryngologist at Baylor Scott & White.

“I would hope that a large portion of them would be like other viral illnesses and a lot of them would recover over time. But it’s not unusual in other viral illnesses for the loss of smell to be permanent,” she said.

1 in 10 COVID-patients who lose their sense of smell may not get it back (KXAN)

According to the CDC, people infected with the coronavirus may start experiencing symptoms between two and 14 days after exposure.

A sudden inability to smell or taste can be a sign that you have COVID-19. For some people, it is the only symptom of the virus that they experience.

Dr. Arffa explained that the median time for recovery of those senses is a week and within three weeks, about 90% of patients can smell and taste again.

The outlook is less clear for the remaining 10% as the virus has simply not existed for long enough to provide enough data about long-term effects.

In general, losing the sense of smell is linked to a nerve injury that may be caused by inflammation.

“We tell people with acute loss of smell from a viral illness in general that up to a year after the loss it still may recover,” Dr. Arffa said.

“It may take up to a year for that nerve that was injured to recover its function.”

For some patients, a course of steroids can help to reduce that inflammation. Others with a more long-term loss of senses can undergo smell retraining therapy.

While that may sound complicated, it’s essentially practicing smelling.

How does smell retraining therapy work?

Dr. Arffa explained how smell retraining therapy can help people with a new loss of smell.

“In all the research that’s been done on smell loss for any cause, that is one of the best things that has been shown in multiple papers to actually work,” she said.

“The idea is that if that nerve is injured you’re encouraging your brain to use that nerve as much as possible to try and encourage it to recover.

“Basically, the idea is getting different strong scents – usually essential oil, things like rose and peppermint, very different scents – and practicing smelling those every day.

“In some people, that actually helps,” she added.