COVID-19 has a variety of different symptoms. One is loss of smell and taste.

Additionally, some people may also experience parosmia after having COVID-19. Parosmia is a smell disorder where odors become distorted.

In this article, we cover what we know so far about parosmia after COVID-19, including potential causes, duration, and treatment.

COVID-19 vaccines cannot cause parosmia

COVID-19 vaccines cannot cause parosmia because none of the currently authorized COVID-19 vaccines contain live SARS-CoV-2, the coronavirus that causes COVID-19.

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Parosmia is a type of smell disorder in which odors become distorted. For example, something that once smelled pleasant may smell bad or rotten to a person with parosmia.

Because smell and taste are so closely linked, parosmia can also have a negative impact on taste and eating. For someone with parosmia, foods that were previously appetizing can become unpalatable.

Potential causes of parosmia

Parosmia can have a variety of causes, including:

How parosmia can affect quality of life

Experiencing parosmia can have a big impact on quality of life. For example, people with parosmia may also have:

Parosmia can also affect a person’s life in other ways. For example, some jobs may be hard to do, particularly if scents are important. Examples of occupations that may be affected include chefs, florists, and firefighters.

There’s also an increased risk of not noticing hazards at home, like not being able to smell burning food, smoke, or gas.

Some people experience parosmia after having COVID-19. In fact, changes in smell or taste like parosmia are one of the many potential symptoms of long-haul COVID-19.

Some types of distorted odors people with parosmia report include:

  • sewage or garbage
  • rotten meat or eggs
  • smoky or burnt
  • gasoline
  • metallic
  • ammonia or vinegar
  • moldy socks
  • skunk

Who’s at risk for getting parosmia after COVID-19?

If loss of smell and taste was one of your acute COVID-19 symptoms, you may be at increased risk of parosmia. In many cases, people with parosmia also experienced loss of smell and taste while they were sick with COVID-19.

Age and sex may also be a factor. One study involving 268 people with parosmia after COVID-19 found that 70.1 percent of them were age 30 or younger, and 73.5 percent were female.

How common is parosmia after COVID-19?

Researchers are still trying to determine how common parosmia after COVID-19 actually is. One June 2021 survey found that out of the 1,299 survey respondents, 140 of them (10.8 percent) reported having parosmia after COVID-19.

The same study found that half of these people reported a sudden onset of parosmia, while the other half reported a gradual onset.

Additionally, the five most common types of foods that triggered parosmia were:

  • chicken and meat
  • onions
  • eggs
  • garlic
  • rice

Generally speaking, parosmia after COVID-19 can gradually fade with time. However, it may take weeks or months to see an improvement.

For example, in the survey study covered above, 49.3 percent of people reported that their parosmia improved within 3 months. The remaining 50.7 percent said their parosmia lasted over 3 months.

A May 2021 study found that participants reported parosmia that lasted anywhere between 9 days and 6 months. The average duration of parosmia was 3.4 months.

The exact way in which COVID-19 causes parosmia is still unknown. However, researchers do have some thoughts on this topic.

While some problems with sense of smell could be from the effects of inflammation in the roof of the nose, it doesn’t explain more persistent, lingering problems with smell like parosmia.

It’s possible that infection with the coronavirus damages the receptors and nerves involved with our sense of smell. While this damage can often be repaired over time, it may cause some disruption in how we perceive odors.

It’s estimated that humans have 350 types of smell receptors. Additionally, our brain identifies individual odors based off of a combination of different signals from these receptors.

Repair of this complex system may occur in a trial-and-error process, which can result in a distorted sense of smell. Think of it as trying to rewire something in your house: It may take you a while to find the optimal connection again.

Why COVID-19 vaccines don’t cause parosmia

It’s important to note that COVID-19 vaccines cannot cause parosmia.

During an infection, the coronavirus is believed to cause damage to the tissues involved with your sense of smell, potentially resulting in parosmia.

However, none of the currently authorized COVID-19 vaccines contain live virus. Instead, the vaccines provide instructions to your cells on how to make a single viral protein called spike protein.

When cells produce spike protein and display it on their surface, the immune system can recognize it as foreign. This prompts an immune response that can protect you from the coronavirus in the future.

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Parosmia due to COVID-19 often resolves on its own over time. But you may be wondering what else you can do as you recover.

Smell training

A technique called smell training may be used to treat parosmia due to COVID-19. You may also see this referred to as olfactory training.

Smell training involves sniffing the same group of scents for 20 seconds at a time. This is typically done at least twice per day for 3 months or longer.

It’s recommended that the scents selected for smell training have different qualities. These include:

  • fruity
  • flowery
  • spicy
  • resinous

Some common scents used for smell training are essential oils of:

You can also choose your own scents from around the house. It may be helpful to pick scents you enjoyed or that may bring back memories. For example, if you’re an avid coffee drinker, you may select coffee grounds as one of your scents.

Switching your scents after several weeks may also help. A 2015 study involving people with smelling dysfunction after an infection found that switching scent groups at 12 and 24 weeks helped them better identify different odors.

In the June 2021 survey discussed earlier, 40 of the 140 survey respondents with parosmia reported receiving smell training for their parosmia. Of these people, 20 said they experienced an improvement in their condition.

Lifestyle changes

Making various lifestyle changes may also help as you recover from parosmia. These typically involve avoiding certain scents that may trigger it. For example:

  • Limit preparation or consumption of certain foods that commonly trigger parosmia, such as meats, onions, or eggs.
  • Focus on blander food items, such as oatmeal or steamed vegetables, which may be less likely to trigger parosmia.
  • Eat foods that are cold or at room temperature, as heat can enhance scents.
  • Aim to avoid areas that are associated with strong scents, such as the grocery store, restaurants, or the perfume counter at a department store.
  • Open the windows or use a fan to help dissipate scents that trigger parosmia.

Parosmia is when scents become distorted. For example, to someone with parosmia, a flower may smell like rotting meat.

Parosmia is a potential symptom of long-haul COVID-19. It’s believed to develop from damage that occurs to the tissues involved in smell during infection with the coronavirus SARS-CoV-2.

Generally speaking, parosmia can go away with time. However, this may take weeks or months. Trying out smell training and avoiding scents that trigger your symptoms may be helpful as you recover from parosmia after COVID-19.