COVID-19 is a respiratory infection that typically causes flu-like symptoms, but one review of studies found 47 percent of people who have it develop changes in their taste or smell.
Some people develop a distorted sense of smell, a condition called parosmia. It sometimes persists for weeks or months after having COVID-19. Some people with parosmia describe everyday odors as “smoky” or unpleasant.
COVID-19 can also lead to another condition called phantosmia, where you experience odors that don’t exist. Some people with COVID-19 also experience hyposmia, which is a loss of smell that can range from partial to total.
Keep reading as we break down why COVID-19 sometimes causes a weird smell in your nose and how long it typically lasts.
Parosmia is a condition characterized by the alteration of your sense of smell. People with parosmia may find:
Parosmia is a potential complication of COVID-19. It may appear by itself or along with other nasal symptoms, like a stuffy or runny nose.
Some people who develop parosmia after having COVID-19 describe experiencing a burned or rotten odor when smelling their usual foods.
A March 2021 case study describes two people who developed parosmia after COVID-19 infection.
The first person, a 28-year-old, was admitted to the emergency room with:
Two days after his diagnosis, he completely lost his sense of smell and taste.
The man started regaining his taste 53 days after having COVID-19. He regained his smell on the 87th day but reported all his smells had a distorted odor like the smell of burned rubber.
The second person, a 32-year-old, was admitted to the emergency room with fatigue and body aches. Six days later she was readmitted with loss of taste, loss of smell, and mild shortness of breath.
Her sense of smell didn’t return until 72 days after acquiring the viral infection. When it did return, she found everyday objects smelled like onions.
Parosmia can potentially persist for weeks or months after developing COVID-19.
In a May 2021 study, researchers examined a group of 268 people who developed parosmia after having COVID-19. They found the participants had smell alteration that lasted from about 10 days to 3 months. Every person in the study either had a partial or complete loss of smell before developing parosmia.
More than 75 percent of people also had an altered sense of taste and only 0.7 percent had other nasal symptoms, such as a runny or stuffy nose.
In another study published in March 2021, researchers found that in a group of 195 healthcare workers with COVID-19, 125 developed dysfunction of their ability to smell, and 118 developed taste dysfunction.
The researchers found that 89 percent of the study participants had full or partial recovery within 6 months, and most of them recovered to some degree within the first 2 months.
The exact mechanism of how COVID-19 causes parosmia remains unclear.
Damage to the olfactory epithelium is thought to contribute. Your olfactory epithelium is the tissue in your nose that receives odors to be processed as sensory information your brain can interpret.
It’s also theorized that damage to the neurons that carry information from your nose to your brain also plays a role.
In the May 2021 study, researchers found that people experiencing a weird smell after having COVID-19 were most likely to describe it in the following ways:
The following were the most common triggers:
Other ways people with parosmia have described their smells include:
Some people with COVID-19 also experience phantosmia, which is when you experience smells that are not really there.
Most people who develop a strange smell after COVID-19 seem to recover within 3 months, according to a study published in May 2021 that reviewed the clinical characteristics of 268 people with confirmed COVID-19 diagnoses at two hospitals in Iraq over a 7-month period.
It’s thought that recovery occurs when your damaged tissues repair themselves.
No particular treatment is known to be able to improve your sense of smell after COVID-19. Avoiding triggers can help minimize your symptoms.
One small study published in August 2021 found that a combination of oral corticosteroids to manage inflammation and olfactory training may help people who develop changes in their smell after having COVID-19. However, more research is needed to back these findings.
Olfactory training involves sniffing a series of strong odors daily to help retrain your ability to smell.
Experiencing a burning smell is sometimes an early symptom of COVID-19, but it isn’t one of the typical symptoms. It’s thought that inflammation inside your nose caused by the viral infection may contribute to its development.
Along with loss or changes in your sense of smell, other COVID-19 nasal symptoms can include a runny or snuffy nose, although they’re not always present in a majority of cases.
A 2020 review of studies found that in a group of 1,773 people with a confirmed COVID-19 diagnosis, only 4.1 percent experienced nasal congestion, and 2.1 percent experienced a runny nose.
It’s a good idea to see a doctor if you’re experiencing phantom smells after having COVID-19 or if everyday odors have a strange scent.
For most people, your sense of smell will likely return when your body is able to fully repair the damage the coronavirus (SARS-CoV-2) caused. A doctor can help you rule out other health conditions that may be contributing factors and recommend ways to help minimize your symptoms.
Some people experience a loss of smell or distorted sense of smell for months after having COVID-19. It’s not entirely clear why some people experience smell alteration, but it’s thought that injury to receptors in your nose and the neurons that lead from your nose to brain may contribute.
Most people seem to regain their sense of smell when their body heals from the damage the coronavirus caused.